M

macadam, tarmac, tarmacadam 1. A paving for roads or other surfaces, formed by grading and compacting layers of crushed stone or gravel; then the top layer(s) are usually bound by asphaltic material, acting to stabilize the stone, provide a smoother surface, and seal against water penetration. 2. The crushed stone used in a macadamized surface.

macadam aggregate A product manufactured by crushing stone, slag, or gravel and then screening it to a uniformly coarse size; when compacted, void spaces are relatively large.

Macassar ebony A hard, very heavy wood of the East Indies; black with red or brown streaks; used for decorative paneling and applications requiring high-impact or wear resistance.

macellum A Roman meat or produce market in a covered hall.

maceria In ancient Roman construction, a rough wall having no facing; constructed in a wide variety of materials.

machicolation An overhanging defensive structure at the top of a medieval fortification, with floor openings through which boiling water or oil, missiles, etc., could be dropped on attackers.

machine bolt A threaded bolt having a straight shank and a conventional head such as a square, hexagonal, button, or countersunk type.

machine burn A darkening or charring of a surface due to overheating of the cutting knives or abrasive belts during machining of the material.

machine finish See smooth machine finish.

machine gouge A groove which results when a machine cuts below the desired line of cut.

machinery room See mechanical equipment room.

macroscopic Visible to the unaided eye.

made ground, made-up ground 1. Solid ground formed by filling in an artificial or natural pit with hard rubble such as broken brick, concrete, etc., or with rubbish. 2. See fill, 1.

made-up ground Same as made ground.

madrasah A theological school, generally arranged around a courtyard, from the 11th cent. A.D. on, in Anatolia, Persia, and Egypt.

maeander See labyrinth fret.

maenianum 1. In ancient Rome, a balcony or gallery for spectators at a public show. 2. Originally, the balcony in the Forum at Rome, for spectators of the gladiatorial combats.

magazine A storage place for ammunition and explosives; also see powder house.

magazine boiler A coal- or coke-fired boiler (in a hot-water or central heating system) which has a bunker fitted to it, large enough to contain 24 hours of fuel.

magnesia A fine white powder of magnesium oxide; gives brick a yellow tint.

magnesia cement Magnesium oxide mixed with water, often with the addition of asbestos fibers; used to cover steam pipes, furnaces, etc.

magnesia insulation Magnesium carbonate hydroxide, with or without admixture of fiber reinforcement or other materials; a good thermal insulator because of the great number of closed air cells it contains; molded into rigid boards, blocks, or shapes conforming to piping.

magnesite A natural magnesium carbonate.

magnesite flooring A flooring material composed of calcined magnesite, magnesium chloride, sawdust, ground quartz or silica, and fine powdered wood waste; used as a finishing surface on concrete floor slabs.

magnesium A gray-white, light metal (64% the weight of aluminum); easily drawn and machined; immune to alkalies.

magnesium alloy Any of a number of alloys of magnesium; the usual additives are aluminum, manganese, silicon, silver, thorium, and zirconium, used singly or in combination.

magnesium carbonate See magnesia insulation.

magnesium hydroxide A white powder which is slightly soluble in water; in dolomitic-type limes used in plaster, its presence helps the lime to spread more easily.

magnesium lime Lime manufactured from limestone; contains some magnesium; used as finish lime in plastering or as mason’s lime in mortar.

magnetic bearing The bearing, 4 of a line where the reference meridian is the local magnetic meridian.

magnetic catch A door catch that uses a magnet to hold the door in a closed position.

magnetic core See core, 11.

magnetic declination At a particular location, the horizontal angle between true meridian (true north-south line) and magnetic meridian (direction of compass needle).

magnetic switch An electric switch whose switch contacts are controlled by means of an electromagnet; esp. used in the control circuits for motors.

magnetite A natural black oxide of iron, containing from about 65 to 72% iron and sometimes a small amount of nickel and titanium; used as an aggregate in high-density concrete.

mahlstick, maulstick A stick used by painters as a rest for the hand while painting.

mahogany 1. A straight-grained wood of intermediate density, pinkish to red-brown in color; found principally in the West Indies, and Central and South America. Used primarily for interior cabinetwork and decorative paneling. 2. Wood from a number of tropical species which resemble mahogany, generally classified as to origin, i.e., African mahogany, Philippine mahogany, etc.

maiden tower The keep or principal tower of a castle.

mail box A multiple arrangement of boxes for receipt and/or distribution of mail at a central point in a building; mainly used in apartment or office buildings.

mail chute, letter chute A small shaft for conducting letters from an upper floor to a postbox on the ground floor.

mail slot, letter slot A small opening, often with a hinged closer, which is set in an exterior door, sidelight, etc., and through which mail is delivered.

main 1. In an air-conditioning system, a major duct or pipe for distributing to or collecting from various branches. 2. In any system of continuous piping, the principal artery of the system to which branches may be connected.

main bar A steel reinforcing bar in main reinforcement.

main beam A principal beam used to carry a load, which transmits the load directly to the columns.

main cable An electric cable which distributes power to a group of buildings.

main contractor Same as general contractor.

main couple The principal truss in a roof.

main diagonal A diagonal member of a web, joining the top and bottom chords of a truss.

main member, primary member In a structural system, a member or component part which is essential to the overall stability of the structure.

main rafter A common rafter.

main reinforcement In reinforced concrete, steel reinforcement which resists stresses resulting from applied loads and moments, as opposed to reinforcement intended to resist secondary stresses.

main runner A large supporting runner for a suspended ceiling; a primary member of the suspension system; usually 1½-in. (3.8-cm) metal channels, held by hangers or rods from the building structure; used to support furring channels or rods to which lath is attached.

main sewer 1. A public sewer. 2. A sewer to which one or more branch sewers are connected and which serves a large area; also called a trunk sewer.

main stack Same as vent stack.

maintainer Same as motor grader.

maintenance The upkeep of a building and its equipment so that the building can continue to perform its required functions. See condition-based maintenance, corrective maintenance, deferred maintenance, emergency maintenance, periodic maintenance, planned maintenance, preventive maintenance, scheduled maintenance.

maintenance bond A bond that provides a guarantee to an owner that the contractor will rectify defects in workmanship or materials reported to the contractor within a specified time period following final acceptance of the work under contract.

maintenance curve For a light source, same as life performance curve.

maintenance factor The ratio of illumination on a given area after a period of time to the initial illumination on the same area; used in lighting calculations to account for the depreciation of lamps or reflective surfaces (or the like). Also see light loss factor.

maintenance finish A heavy-duty paint, varnish, or lacquer used to protect and decorate industrial, institutional, and commercial buildings and structures.

main tie In a roof truss, a member which connects the feet of the rafters.

main trap See building trap.

main vent The principal artery of the venting system to which vent branches may be connected; also called vent stack.

maison de maître See Creole house.

maison de poteaux-en-terre See poteaux-en-terre house.

maisonette Same as duplex apartment.

maison pièce sur pièce 1. In French vernacular architecture of Louisiana, primarily in the 18th century, a dogtrot cabin consisting of two single-room cabins separated from each other by an open passageway which both cabins shared. 2. A one-room log cabin. See also pièce sur pièce construction.

majolica A type of pottery decorated with an opaque white glaze and a colored overglaze; a type of faïence tile.

makeup air Outdoor air which is supplied to an HVAC system to replace exhaust air and any air lost by exfiltration.

makeup water Water which is supplied (as to a steam boiler or cooling tower) to compensate for losses by evaporation and leakage.

makore, African cherry, cherry mahogany A moderately hard, heavy wood of West Africa, pinkish to red-brown in color; resembles mahogany and American cherry; used for cabinets, flooring, and plywood.

maksoorah In a mosque, an area which is enclosed by a screen or partition and which is reserved for prayer or surrounds a tomb.

malachite A carbonate of copper; green in color; harder than marble; usually employed as a highly polished veneer.

male connector Any type of electrical connector having contacts which project into the recessed opening of a female connector.

male plug An electric plug, 5 inserted into a receptacle to form an electric connection.

male thread 1. A thread on the outside of a pipe. 2. Same as external thread.

mall 1. A public plaza, walk, or system of walks, often set with trees and designed for pedestrian use. 2. See shopping mall. 3. A heavy wood mallet; a maul.

malleability The property of a metal that permits mechanical deformation by extrusion, forging, rolling, etc., without fracturing.

malleable brass Same as Muntz metal.

malleable iron 1. A white cast iron that has been annealed; malleable cast iron. 2. Wrought iron. A low-carbon cast iron that has been annealed and allowed to cool slowly; capable of being beaten into shape to form decorative iron-work.

mallet A short-handled wooden hammer, used by carpenters, stonecutters, etc., chiefly for driving another tool, as a chisel; the head may be of a soft material such as plastic.

mallet-headed chisel A steel mason’s chisel having a rounded head.

malm 1. Earth containing a considerable quantity of chalk in fine particles; a calcareous loam. 2. A malm brick.

malm brick A brick made of true or artificial malm, the latter consisting of comminuted chalk mixed with sand and pan breeze.

malm rubber A relatively soft malm brick which can be rubbed to a desired shape.

Maltese cross A cross formed by four equal triangles or arrowheads joined at their points.

maltha 1. In ancient Roman construction, a type of bitumen, various cements, stuccos, and the like, used for repairing cisterns, roofs, etc. 2. A bituminous substance midway in consistency between asphalt and petroleum.

malus In ancient Roman theaters and amphitheaters, one of the poles over which the velarium was stretched.

MAN. On drawings, abbr. for “manual.”

mandapa A large, open porch or hall of a Hindu temple.

mandatory and customary benefits See benefits.

mandatory standard A standard with which it is obligatory to comply; established by an authority endowed with the necessary legal power.

mandoral Same as mandorla.

mandorla, vesica piscis An aureole, almond-shaped, depicted around the full form of a sacred person.

mandrel, mandril 1. A temporary internal support for a light-gauge metal shell during a pile-driving operation; takes the impact of the pile hammer during driving and is then withdrawn before concrete is placed in the shell; also called a pile core. 2. A cylindrical bar or spindle, used chiefly as a support during machining or forming operations.

manganese A metallic element used as an alloying element in steel as a hardener and deoxidizer; also used as an alloying element in other metals such as copper to introduce high mechanical damping.

manganese drier Manganese acetate used in paints to speed its rate of drying.

manganese greensand See greensand.

manganese steel A very hard, brittle steel containing from 11 to 14% manganese and 1.5% carbon; must be treated by cooling in water to remove extreme brittleness; used where high resistance to abrasion is necessary.

manger A trough in a stable for feeding cattle.

manhole A covered opening in a street which provides access for cleaning and repairing of a sewer beneath, or for repairing a conduit for electric underground piping or electric cables.

man-hour A unit of work equal to the output of one man working for 1 hour.

manifold A section of duct, a fitting, or a pipe with a number of branches which are close together.

Mannerism Transitional style in architecture and the arts in the late 16th cent., particularly in Italy, characterized in architecture by unconventional use of classical elements.

manometer An instrument for the measurement of pressure; a U-shaped glass tube partially filled with water or mercury, one side of which is connected to the source of pressure. The amount of displacement of the liquid is a measure of the magnitude of the pressure.

manor house 1. Usually, an imposing house in a countryside, often the residence of a landowner with considerable acreage. 2. A relatively simple one-room house of early colonists in America, having a gable roof, clapboard walls, a battened door, a window at the front of the house with solid shutters, and a chimney at one or at each end.

mansard roof 1. (US and Brit.) A roof having a double slope on all four sides, the lower slope being much steeper. 2. (US) Same as gambrel roof. 3. A hipped roof usually having a double slope or compound curve on all four sides of the roof, the lower slope usually being much steeper than the upper slope; alternatively, the sides may have a concave-, convex-, or S-shape. 4. A sloping roof that projects from the wall of a building and has a double slope, the lower slope being steeper than the upper.

Mansard style 1. A term sometimes used as a synonym for Second Empire style in the United States. 2. An architectural style that makes use of, or suggests, a mansard roof.

manse The dwelling of a clergyman.

mansion 1. A very large, imposing, stately residence. 2. In colonial times, the residence of a landholder. 3. A manor house; also called a mansion house.

mantel 1. A beam or arch that supports the masonry above a fireplace; also called a manteltree. 2. All the construction or facing around a fireplace. 3. A mantelshelf.

mantel board A wood mantelshelf.

mantelpiece 1. The fittings and decorative elements of a mantel above a fireplace. 2. A shelf above a mantel; often called a mantelshelf. 3. The construction that serves as a support for the masonry above a fireplace. 4. A mantelshelf.

mantel register, cast-iron register A relatively inexpensive prefabricated cast-iron mantelpiece which screws onto the fireplace and forms the fireplace surround.

mantelshelf That part of a mantelpiece which constitutes a shelf.

manteltree A wood, stone, or iron structural member that spans the opening over a fireplace. Often, a large horizontal oak timber that serves to support the wall construction above, typically placed high enough above the hearth to prevent its igniting; sometimes plastered to improve its fire resistance.

mantle 1. Same as mantel. 2. The outer covering of a wall which differs from the material of the inner surface.

mantlet Same as chemise.

mantonium A fireproofing plaster composed of equal parts of gypsum and exfoliated vermiculite; applied to structural steel elements as fireproofing.

mantrap A short narrow section of corridor purposely constructed to permit passage by only one person; has interlocking doors at both ends; used in some high-level security installations.

manual batcher A batcher equipped with gates or valves which are operated manually.

manual call point A British term for fire alarm box.

manual fire alarm system A fire alarm system that is manually operated, so arranged that the operation of any one station will ring all signals throughout the building as well as at one or more selected locations.

manual fire pump A pump supplying water to a sprinkler or standpipe system which is not activated automatically and must be started by hand.

manually-propelled mobile scaffold See mobile scaffold.

manual operation Said of functioning of equipment or devices that are capable of being operated directly by hand without any other source of power.

Manueline architecture The last phase of Gothic architecture in Portugal, so named after King Manuel I (1495–1521).

manufactured building A structure which is substantially or wholly made in a manufacturing plant for installation or assembly at a building site.

manufactured home A manufactured building intended as a dwelling.

manufactured house Same as prefabricated house.

manufactured sand A fine aggregate produced by crushing rock, gravel, or slag.

map A graphic, planar depiction of the earth’s surface, or a portion thereof, drawn to scale.

map cracks, map cracking See checking.

maple A hard, tough, moderately high-density wood of North America and Europe, light to dark brown in color; has a uniform texture; used for flooring, wood turning, etc. Also see bird’seye maple.

maqsura An enclosure in a mosque which includes the praying niche, made usually of an openwork screen; originally meant for the sultan during public prayers.

marb Abbr. for marble or “marbleized.”

marble A metamorphic rock composed largely of calcite or dolomite; often highly polished to enhance its appearance; available in different colors that result from differences in mineral content.

marbled, marbleized Having the appearance of marble, or made to look like marble by a special application of paint, as in marbleized woodwork, or by integral treatment, as in marbleized plastic tile.

marbling, marbleizing The use of antiquing techniques to achieve the appearance of marble in a paint film.

marezzo, marezzo marble A cast imitation marble produced with Keene’s cement. Also see artificial stone.

margin 1. The exposed flat surface of the stiles and rails which form the framing around a panel. 2. The projecting surface above the stair nosings in a close string. 3. The mitered border around a hearth. 4. The exposed surface of a slate or tile which is not covered by the one above.

marginal bar A glazing bar which divides a glazed opening so that a central glazed opening is surrounded by narrow panes at the edges.

margin draft In masonry, the plain-dressed border on the face of a hewn block; the middle part of the face may be dressed or left rough; also see draft, 2.

margin light See side light.

margin of safety Same as factor of safety.

margin strip In flooring, a wood member which forms a border.

margin trowel A plasterer’s trowel which has a box-like shape or sides which turn up so that it is especially useful for working corner angles.

marigold window A round window whose mullions of tracery radiate; a rose window.

marine glue Any glue which is insoluble in water; usually contains a solution of rubber and/or resins.

marine paint A paint formulated to withstand exposure to sunlight and to fresh and salt water.

marine plywood Plywood in which the layers of veneer (i.e., plies) have been cemented to each other with a marine glue.

marked face The front or face side of a piece of lumber.

marker A sign, plaque, or monument that designates a building, site of historic importance, or boundary.

market cross Same as cross, 2 or a cross located at the principal market place of a town.

market house, market hall Often, a one- or two-story rectangular building where butchers, fishmongers, grocers, and peddlers sell their goods on the ground floor often open to the outdoors; sometimes arches or heavy posts support a second story that may house municipal offices.

marketplace A building or open place in which produce, usually of local origin, is sold.

marking gauge, butt gauge A carpenter’s tool for scribing a line parallel to an edge; consists of an adjustable faceplate (which is run along the edge) mounted on a rod containing a marking point.

mark out In carpentry, to lay out the lines where cuts are to be made.

marl An earthy deposit; a mixture of clay and carbonate of lime.

marl brick, marl stock A superior brick made from marl.

marmoratum In ancient Roman construction, a cement formed of pounded marble and lime mortar which were well mixed; used in building walls, terraces, etc.

marmoset, marmouset An antic figure, usually grotesque, introduced into architectural decoration in the 13th cent.

marouflage A technique for fastening canvas (or the like) to a wall by means of an adhesive.

marquee, marquise A permanent roof-like shelter over an entrance to a building.

marquetry Inlaid pieces of a material, such as wood or ivory, fitted together and glued to a common background. Also see inlay and intarsia.

martello tower A defensive tower of the 16th century; of Italian origin and usually circular.

martin hole See owlhole.

Martin’s cement, hard-finish plaster Similar to Keene’s cement but contains potassium carbonate as an additive in place of alum.

martyrium A place where the relics of a martyr are deposited.

mascaron, mask The representation of a face, a human or partly human head, more or less caricatured, used as an architectural ornament.

mascaron stop A termination at the end of a molding over a door or window. Also called a mask stop.

mash hammer, mash In stoneworking, a short-handled heavy hammer with two round or octagonal faces.

mashrebeeyeh See meshrebeeyeh.

mask See mascaron.

masking 1. Preparing surfaces adjacent to paintwork with a temporary covering of masking tape, or tape plus paper, to keep them free of paint. 2. Screening off part of a theater stage from view of the audience. 3. The action of rendering one sound inaudible or unintelligible as the result of the presence of another (usually louder) one.

masking tape An adhesive-backed paper tape used in masking, 1.

mason A person who is skilled in the craft of building with units of natural or artificial mineral products, such as bricks, stones, and cinderblocks, that are usually bonded or cemented with mortar to similar units.

Masonite A proprietary name for a widely used commercial hardboard.

masonry 1. The art of shaping, arranging, and uniting stone, brick, building blocks, etc., to form walls and other parts of a building. 2. Construction using masonry units of such materials as clay, shale, glass, gypsum, or stone, set in mortar; this term includes concrete masonry units but excludes reinforced concrete.

masonry anchor The metal piece inside the throat of a hollow-metal doorframe which secures the frame to a masonry wall.

masonry block Same as masonry unit.

masonry bond See bond.

masonry-bonded hollow wall A wall built of masonry units so arranged as to provide an air space within the wall, and in which the facing and backing of the wall are bonded together with masonry units.

masonry cement Hydraulic cement for use in mortars for masonry construction where greater plasticity and water retention are desired than are obtainable by the use of portland cement alone; such a cement always contains one or more of the following materials: portland cement, portland-pozzolan cement, natural cement, slag cement, and hydraulic lime, and usually contains one or more of the following: hydrated lime, pulverized limestone, chalk, talc, pozzolan, clay, and gypsum; many masonry cements also include entrained air and a water-repellent.

masonry course A layer of masonry units running (essentially) horizontally in a wall.

masonry cramp A U-shaped metal fastener used to hold adjacent units of masonry together.

masonry drill Same as star drill.

masonry filler unit A masonry unit which is used to fill the space between joists or beams, providing a platform for a cast-in-place concrete slab.

masonry grout Any cementitious mixture used to fill voids in masonry.

masonry guard A plaster guard.

masonry joint Any joint between masonry units bonded with mortar. See colonial joint, concave joint, excess joint, extruded joint, flat joint, flush-cut joint, hick joint, hungry joint, keyed joint, raked joint, rodded joint, rough-cut joint, ruled joint, scored joint, scribed joint, skintled joint, spalled joint, struck joint, tooled joint, troweled joint, V-joint, weather joint, weather-struck joint. Also see pointing.

masonry mortar See masonry cement and mortar.

masonry nail A hardened-steel nail with a knurled or fluted shank; esp. used for fastening to masonry.

masonry paint A durable paint expressly designed to coat exterior masonry surfaces. Also see cement paint.

masonry panel See prefabricated masonry panel.

masonry reinforcement See reinforcement.

masonry tie 1. See wall tie. 2. See tie, 1.

masonry unit A building unit fabricated of burnt clay, concrete, stone, or the like.

masonry veneer A masonry facing laid against a wall and not structurally bonded to the wall.

mason’s adjustable multiple-point suspension scaffold A scaffold having a continuous platform supported by bearers suspended by wire rope from overhead supports, so arranged and operated as to permit the raising or lowering of the platform to desired working positions.

mason’s ax See axhammer.

mason’s hammer A hammer with a heavy steel head, one face of which is shaped like a chisel for trimming brick or stone.

mason’s joint Same as mason’s V-joint pointing.

mason’s lead See lead, 1.

mason’s level A level similar to a carpenter’s level but longer.

mason’s lime See building lime.

mason’s mark See banker-mark.

mason’s measure A measure of the quantity of masonry units required for a job; corners are counted twice, and no allowance is made for small openings.

mason’s miter, mason’s mitre A masonry joint having the appearance of a miter joint but actually shaped from a single solid stone.

mason’s putty A lime putty to which portland cement and stone dust have been added; esp. used in ashlar work.

mason’s scaffold A totally self-supporting scaffold, having two rows of standards, capable of carrying unusually heavy loads.

mason’s stop Same as mason’s miter.

mason’s V-joint pointing Pointing in which the mortar is given a profile similar to a flattened V; may also have a flat fillet at top and bottom.

masonwork Same as masonry.

mass bell Same as sanctus bell.

mass burning rate The loss of mass per unit by materials burning under specified conditions.

mass center Same as center of gravity.

mass color When viewed by reflected light, the color of a pigment-vehicle mixture which is thick enough to completely obscure the background.

mass concrete Any volume of cast-in-place concrete intended to resist applied loads by virtue of its mass; generally cast as a monolithic structure; usually incorporates a high proportion of large coarse aggregate and a low cement content.

mass curing The adiabatic curing of concrete in sealed containers.

mass diagram A calculation employing a graph portraying the cumulative quantities of cut and fill along the center line (cut is shown as a positive quantity and fill is shown as a negative quantity); used to determine the haul.

mass foundation Any support for a structure which is enlarged beyond the size required for adequate strength; used to provide additional inertia to dissipate or alleviate the undesirable effects of vibration or impact.

massicot A yellow amorphous powder, the crystalline form of which is litharge; used as a pigment.

mass retaining wall A gravity wall.

masstone The undiluted color of a pigment or pigmented paint film.

mast 1. A tower which carries one or more load lines. 2. The load-bearing component of a derrick, or the like.

mastaba A freestanding tomb used in ancient Egypt, consisting of a rectangular superstructure with inclined sides, from which a shaft leads to underground burial and offering chambers.

mast arm A bracket attachment to a lamppost or pole from which a luminaire is suspended.

MasterFormat As illustrated in the definition of contract documents, a uniform classification system for construction specifications that is divided into 16 sections, each of which is numbered and named.

master key A key that will operate a number of different locks, each of which is different.

master mason An exceptionally well-qualified mason in the Middle Ages; a position more or less equivalent to that of an architect today.

master plan A plan, usually graphic and drawn on a small scale but often supplemented by written material, which depicts all the elements of a project or scheme.

master plumber An individual licensed and authorized to install and to assume responsibility for contractual agreements pertaining to plumbing, and to secure any permits required for plumbing installations.

MASTERSPEC A proprietary master specification for the construction industry developed by the American Institute of Architects.

master switch A single electric switch in a wiring system which controls the supply of power to a building, or the action of relays or any other remotely operated devices.

mastic 1. Any heavy-bodied, dough-like adhesive compound. 2. A sealant with putty-like properties. 3. A protective coating applied by trowel or spray on the surface of thermal insulation to prevent its deterioration and to weatherproof it.

mastic asphalt See asphaltic mastic.

mat 1. See matte. 2. See mattress. 3. A very heavy, flexible blanket of steel mesh, woven wire rope, or chain; used to confine fragments of rock during blasting.

match In comparing two materials or constructions: an exact or approximate replication.

matchboards Boards which have a tongue along one edge and a groove along the other; when installed, the tongue of one board fits into the corresponding groove of the adjacent board and holds it securely. Also see dressed and matched boards.

matched floor A floor laid with matchboards.

matched joint, match joint The joint along the edge between two matchboards.

matched lumber Lumber having dressed edges and prepared for tongue-and-groove joints.

matched roof boards Matchboards used as roof sheathing.

matched siding Same as drop siding.

matching A system of matchboards, or of sheets of wood veneer, arranged to emphasize grain pattern, as in book matching or herringbone matching.

match plane One of a pair of planes used to prepare matchboards; one cuts the tongue along the edge, and the other cuts the groove.

material costs The total costs of all materials used on a construction project, including delivery, handling, waste, storage, and taxes.

material hose Same as delivery hose.

material platform hoist A suspended platform, manually or power operated, for conveying building materials and supplies; usually controlled from a point outside the conveyance.

material sample A small piece of material, which is representative of the whole, that a contractor submits to the architect for approval; includes color, finish, and/or texture.

materials cage An open platform on a vertical hoist, used for lifting materials to upper floors during construction of a building.

materials tower Same as hoist tower.

material supplier Same as supplier.

materiato A collective term for all timberwork employed in Classical Roman roof construction.

mat foundation A large, thick concrete slab that sustains the load imposed by a number of columns and/or walls; also called a raft foundation or floating foundation.

Matheson joint In wrought-iron pipe, a bell-and-spigot joint.

MATL On drawings, abbr. for “material.”

matrix 1. In mortar, the cement paste in which the fine aggregate particles are embedded. 2. In concrete, the mortar in which the coarse aggregate particles are embedded.

matroneum In some religious settings which do not allow the sexes to mingle, a gallery set aside for women.

mat sink Same as mat well.

matsu A common Japanese pine; used in house construction.

matte, mat, matt A surface finish which is dull, with little or no gloss or sheen, and with low light reflectivity.

matte dip A liquid dip composed of two parts by volume of sulfuric acid to one part by volume of nitric acid and saturated with zinc oxide or sulfate; used to obtain a matte finish on metals.

matte-surfaced glass Glass, one or both sides of which have been etched, ground, sandblasted, etc., to provide diffusion of light.

matte varnish See flat varnish.

mattock A tool for loosening soil in digging; shaped like a pickax, but having one of its ends broad instead of pointed.

mattress A layer or slab of concrete, laid directly on the ground, which acts as a footing or the like.

mature tree A tree having a trunk diameter greater than that specified in the applicable code.

maturing The aging and/or proper hardening of a material, e.g., mortar, plaster, concrete, etc.

maturing bin See boiling tub.

maturity A measure of the developing of strength in concrete; combines the effects of curing temperature and time of hydration.

mat well At the entrance of an exterior door, a depression in the floor to hold a fiber doormat.

maul, mall 1. A heavy, wooden mallet. 2. See beetle.

maulstick A mahlstick.

mausoleum 1. A commemorative edifice for the reception of a monument; a cenotaph. 2. A sepulchral chapel to contain tombs.

MAX On drawings, abbr. for “maximum.”

maximum acceptable pressure In a water distribution system, the highest water pressure that will not result in the premature or accelerated damage of any component in the system.

maximum demand 1. The greatest load, 3 delivered to an electric system over a definitely prescribed time interval. 2. The greatest flow of water (or waste discharge) for all the fixtures in a plumbing system in a building during a definitely prescribed time interval.

maximum overall length 1. For a lamp bulb having a single base, the dimension from the base to the point on the bulb farthest away. 2. For a lamp bulb with a base at each end, the maximum dimension from base to base.

maximum rated load As applied to scaffolds, the total of all loads including the working load, the weight of the scaffold, and such other loads as may be reasonably anticipated.

maximum size of aggregate The largest size of aggregate particles present in sufficient quantity to affect the physical properties of concrete; generally designated by the sieve size on which the maximum amount permitted to be retained is 5 or 10% by weight.

maximum temperature period In autoclave curing, the time interval over which the maximum temperature is held constant.

maximum working pressure The maximum pressure at which piping materials of the “standard” or “normally used” type are safe to use.

may A term which denotes an option or alternative. Compare with shall and should.

Maya architecture The architecture of the Mayan people in Central America and Mexico from the 4th to the 15th cent., principally of pyramid temples with steep stairways.

Mayan arch A corbeled arch of triangular shape common in the buildings of the Maya Indians of Yucatán.

maze Same as labyrinth, 3.

M.b.m., MBM In the lumber industry, abbr. for “thousand (feet) board measure.”

MC 1. Abbr. for “moisture content.” 2. Abbr. for “metal-clad.” 3. Abbr. for “mail chute.”

MC asphalt Same as medium-curing asphalt.

MCM Abbr. for “thousand circular mills.” See wire size.

meager lime Low-purity lime containing at least 15% impurities.

meal house A structure once used for storing grain that had been ground.

meander Same as Greek key.

meandering shear wall A shear wall that is irregular in plan.

mean gradient Average slope (for example, of a water pipe or drain pipe).

means of egress A continuous path of travel from any point in a building or structure to the outside at ground level.

means of escape See fire escape.

measured drawing An architectural drawing of an existing building, object, site, structure, or detail thereof; accurately drawn to scale on the basis of field measurements.

measurement standard A prescribed procedure for conducting a measurement in such a way as to obtain reliable, reproducible results with a specified level of accuracy.

measuring chain 1. See chain. 2. See Gunter’s chain.

measuring frame Same as batch box.

meat house Same as smoke house.

MECH On drawings, abbr. for “mechanical.”

mechanical analysis The process of determining particle-size distribution in an aggregate or in a soil, sediment, or rock. Also see sieve analysis and particle-size distribution.

mechanical application The application of plaster or mortar by pumping and spraying, rather than by hand with a trowel.

mechanical bond 1. The keying of a plaster coat: (a) with another coat or a plaster base below or (b) as a result of plaster which is partially troweled through metal lath. 2. In reinforced concrete construction, a bond between concrete and specially shaped steel reinforcing bars or rods.

mechanical connection The joining of two or more elements by mechanical fasteners such as bolts, rivets, or screws (but not by non-mechanical means, such as by adhesives).

mechanical core Prefabricated piping for plumbing and/or heating, prefabricated duct-work, and/or prefabricated electric wiring, ready for field installation with a minimum amount of labor at the site.

mechanical-draft chimney A chimney in which the draft is produced, wholly or partly, by an auxiliary blower that either forces air into the furnace or draws the gases and smoke from the furnace and discharges them into the chimney.

mechanical-draft water-cooling tower A water-cooling tower in which air is moved through the tower by one or more fans built into the tower.

mechanical drawing A precise drawing, produced with the aid of instruments, as compasses, triangles, T-squares, etc.

mechanical equipment room, machinery room A room containing a permanently installed refrigeration or air-conditioning system, or major parts thereof.

mechanical equivalent of heat The number of units of mechanical energy equal to one unit of heat, e.g., 778.2 ft-lb (107.6 kg-m) equals 1 Btu; 4.187 joules equals 1 calorie.

mechanical joint 1. A gastight and watertight joint formed by joining metal parts through a positive-holding mechanical assembly (such as flanged joint, screwed joint, flared joint). 2. In piping, a joint which typically consists of: (a) a flange which is integrally cast with the bell of the pipe, (b) a rubber gasket which fits into the recess in the socket, (c) a follower ring which compresses the gasket, and (d) nuts and bolts used to tighten the joint.

mechanically foamed plastic A cellular plastic whose structure is produced by physically incorporated gases.

mechanically galvanized nail, peen-coated nail A nail which is zinc-coated by tumbling in a container with powdered zinc and small glass beads.

mechanical operator A mechanism for opening and closing side-by-side windows in factories, gymnasiums, etc., either by manual operation with a hand crank, handwheel, or hand chain, or by an electric motor drive.

mechanical property A property of a material that is associated with elastic and inelastic reaction when force is applied, or that involves the relationship between stress and strain.

mechanical room See mechanical equipment room.

mechanical saw See band saw, circular saw, jigsaw.

mechanical stoker A device which automatically feeds a solid fuel (such as coal) into a combustion chamber of a boiler or furnace, and provides air for proper combustion; may include a means for automatically removing solid products of combustion.

mechanical trowel A trowel consisting of power-driven metal or rubber blades for smoothing.

mechanical ventilation The process of supplying outdoor air to a building or removing air from it by mechanical means, e.g., with fans; the air which is supplied may or may not be heated, cooled, or air-conditioned.

mechanic’s lien A lien on privately owned real property created by state statute in favor of persons supplying labor or materials for a building or structure or improvements thereof, generally for the value of the labor or materials supplied by them. In some states, a mechanic’s lien also exists for the value of professional services. Laws differ greatly among states as to the circumstances in which such a lien may arise, the sum for which it may be imposed, and the procedures whereby the sum due may be collected or the lien discharged. In most circumstances, clear title to the property cannot be obtained until the claim on which the lien is based has been settled.

mechanized parking equipment Devices in mechanical parking garages that are used exclusively for conveying automobiles, by means of a power-driven transfer device, directly into parking spaces or cubicles.

MED On drawings, abbr. for medium.

medallion 1. An ornamental plaque (often round, oval, or square, but may be of any other form) representing an object or design in relief, such as a figure, flower, or head. 2. A ceiling ornament, often cast in plaster, at the center of which is often hung a chandelier or luminaire; also called a rose or rosette.

medallion molding A molding consisting of a series of medallions, found in the later and richer examples of Norman architecture.

medicine cabinet A storage cabinet for medical supplies, toilet articles, and the like.

Medieval architecture Architecture of the European Middle Ages, from about the 5th to the 15th centuries. Found, in particular, in the pre-Romanesque, Romanesque, and Gothic styles.

Mediterranean Revival An imprecise term (not a Revival architecture, as the name implies) for a mixture of Mission Revival, Italian Villa style, and Spanish Colonial Revival, particularly in the latter part of the 20th century; usually applied to a one- or two-story house with a red tile roof and stuccoed walls, usually having rounded or arched windows; occasionally referred to as Mediterranean style.

medium The liquid or semiliquid ingredient of a paint which controls ease of application, appearance, gloss, adhesion, durability, and chemical inertness.

medium-carbon steel Steel having a carbon content between 0.3 and 0.6%.

medium-curing asphalt Liquid asphalt composed of asphalt cement and a kerosene-type diluent of medium volatility.

medium-curing cutback See medium-curing asphalt.

medium-density fiberboard, medium-density hardboard Fiberboard having a density of from 30 to 50 lb per cu ft (480 to 800 kg per cu m); used for structural building applications, coreboards, etc.

medium-density overlay An overlay of paper impregnated with a thermosetting resin; applied by a hot-press to plywood, fiberboard, particleboard, etc., usually to improve its appearance and durability.

medium-duty scaffold A scaffold designed and constructed to carry a working load not to exceed 50 lb per sq ft (245 kg per sq m).

medium oil varnish A varnish containing between 5 and 15 gal oil per 100 lb (0.5 and 1.5 liter oil per kg) gum; used for interior paints and varnishes.

medium relief Same as mezzo-relievo.

medium steel Steel neither very hard nor very soft, usually contains from 0.25 to 0.5% carbon.

medium-temperature water-heating system A heating system in which water having supply temperatures between 250°F (121°C) and 350°F (177°C) is used as a medium to convey heat from a central boiler, through a piping system, to suitable heat-distributing devices.

medium voltage According to ANSI/IEEE standards, a nominal system voltage of between 1000 and 72,500 volts.

medullary ray, pith ray In a cross section of a tree or log, one of the ribbons of tissue extending radially from the pith; may vary from microscopic to 4 in. (10 cm) or more in oak; used to store and transport food horizontally within the tree.

meeting house A house of worship for some Protestant faiths; also may serve as a center of community activity; usually a notably plain structure, often having a square floor plan.

meeting post, miter post The outer stile of a lock gate which meets, at the middle of a gateway, the corresponding stile of the companion gate.

meeting rail In a double-hung window, the horizontal member at the top of the lower sash or the horizontal member at the bottom of the upper sash.

meeting stile One of the abutting stiles in a pair of doors or sashes.

megalithic Built of unusually large stones.

megalopolis, megapolis A thickly populated urban region usually consisting of one or more large cities and surrounding suburbs.

megaron 1. In many Greek temples, a space divided off and sometimes subterranean, where only the priest was allowed to enter. 2. The great central hall of a palace.

megascopic Visible to the unaided eye.

megilp In painting, a vehicle made of oil of turpentine and pale drying oil in equal proportions.

mehrab Same as mihrab.

MEK See methyl ethyl ketone.

melamine formaldehyde A colorless alkyd-type synthetic resin which is resistant to alkalies and most acids; used for surfacing plywood, chipboard, etc.

melon dome A melon-like ribbed dome (either an exterior or interior dome), especially found in Islamic architecture.

MEMB On drawings, abbr. for “membrane.”

member In structural engineering, a component part of a structure, complete in itself.

membrane In built-up roofing, a weather-resistant (flexible or semiflexible) covering consisting of alternate layers of felt and bitumen; fabricated in a continuous covering and surfaced with aggregate or asphaltic material.

membrane curing A process in which either a liquid sealing compound (e.g., bituminous and paraffinic emulsions, coal-tar cutbacks) or a nonliquid protective coating (e.g., sheet plastics) functions as a film to restrict evaporation of mixing water from a fresh concrete surface.

membrane fireproofing A lath and plaster membrane that provides resistance to fire and extreme heat.

membrane forces Direct and shear forces that act entirely within a thin concrete shell.

membrane roofing See membrane.

membrane theory In the design of thin shells, a theory assuming that a shell cannot resist bending because it deflects, and that the only stresses in any section are shear stress and direct compression or tension.

membrane waterproofing A membrane applied to a surface to make it impervious to water.

MEMO On drawings, abbr. for “memorandum.”

memorial An architectural or sculptural object or plaque commemorating a person or an event.

memorial arch An arch commemorating a person or event, popular during the Roman Empire, and again at the time of Napoleon and later.

memorial park A cemetery, usually having grave markers flush with the ground in large open meadows bordered by groves of trees.

memorial plaque A flat marker, usually of metal or stone and often inscribed, affixed to or set into a surface; used to serve as a memorial or to commemorate a special event.

memorial stone, memorial tablet A stone or tablet set up, or placed on or in a wall, to commemorate some person or event.

memorial window In a church, a stained glass window dedicated to the memory of a person or family.

memory The quality of a material that enables it to return to its original shape after it has been compressed or stretched.

mending plate A steel strip, usually predrilled with staggered screw holes; used to strengthen joints in wood construction.

menhir A prehistoric monument consisting of a single large standing stone, sometimes rudely sculptured.

mensa 1. The stone slab or other piece forming the top of an altar. 2. The upper surface of an altar.

mensao Same as menhir.

mensole Same as keystone of an arch.

men’s room In a public building, a room containing toilet and lavatory facilities for the use of men.

mensuration 1. The process or art of measuring. 2. The branch of mathematics dealing with the determination of length, area, or volume.

MER Abbr. for mechanical equipment room.

mer The smallest repetitive unit in the structure of a high polymer.

mercantile occupancy The use of rooms, stores, markets, buildings, or structures for the display and sale of merchandise.

merchant bar iron Obsolete name for wrought iron bars and rods.

merchant pipe A pipe which is not of standard full weight; usually 5 to 8% lighter.

mercury-contact switch A wall-mounted switch used in interior electric wiring; contains a sealed glass tube of mercury which provides a silent contact when the switch is turned on.

mercury lamp A high-intensity electric-discharge lamp consisting of an electric arc in mercury vapor in a sealed tube, which in turn may be enclosed in an outer glass envelope; the light produced appears blue-white, but contains only violet, blue, green, and yellow components; usually operates slightly above atmospheric pressure.

mercury switch Same as mercury-contact switch.

mercury-vapor lamp An electric-discharge lamp consisting of an electric arc in mercury vapor in a sealed tube, which in turn may be enclosed in an outer glass envelope; the light produced appears to be blue-white, but contains only violet, blue, green, and yellow components. The lamp is said to be “low pressure” if the partial pressure of the vapor is below 0.001 atmosphere, and “high pressure” if about an atmosphere.

meridian stone A stone placed along a meridian (i.e., an accurately determined line running north and south) to delineate the eastern or western boundary of a town or village.

merlon In an embattled parapet, one of the solid alternates between the embrasures. Also see battlement.

meros The frontal area between two grooves of a triglyph.

mesaulos In an ancient Greek house: 1. A passageway connecting the andron with the gynaeceum. 2. The door in this passageway.

mesh 1. The number of openings per inch in wire cloth; a 100-mesh screen has 100 openings per inch in each direction. 2. A network of metal wires or the like. 3. Expanded metal, light-woven steel, or welded steel used as reinforcement in concrete.

mesh-core door, cellular-core door A hollow-core door of wood construction; the core consists of a cellulose mesh grid or honeycomb which is encased by wood rails and stiles; face panels are fixed to the core with a waterproof adhesive.

mesh partition A partition constructed of a framework which is closed by heavy wire mesh; acts as a barrier against unauthorized entry, but provides for the passage of air, heat, and light; does not obstruct operation of a sprinkler system; used to protect and secure an area, such as a stockroom.

meshrebeeyeh, mashrebeeyeh, moucharaby, mushrabiya 1. An elaborately turned wood screen enclosing a balcony window in an Arabic structure. 2. Such a screen otherwise used. 3. A balcony with a parapet and machicolations projected over a gate to defend the entrance; the parapet may be either embattled or plain.

mesh reinforcement In reinforced concrete, an arrangement of steel bars or wire normally in two directions at right angles, tied or welded at the intersections or interwoven.

Mesoamerican architecture Architecture of the area of Mexico and Central America in which the presence of certain pre-Hispanic cultural traits permits the classification of cultures of the region as one civilization; includes central and southern Mexico, the Yucatán peninsula, Guatemala, El Salvador, and parts of Honduras, Nicaragua, and northern Costa Rica.

Mesopotamian architecture Architecture developed by the Euphrates and Tigris Valley civilizations, from the 3rd millennium to the 6th cent. B.C. Primarily a massive architecture of mud bricks set in clay mortar or bitumen. The heavy walls were articulated by pilasters and recesses; important public buildings were faced with baked or glazed brick. Rooms were narrow and long and generally covered by timber and mud roofs, but in certain cases also by tunnel vaults; columns were seldom used; openings usually were small.

messmate A variety of eucalyptus wood; used as timber for rough work.

messuage A dwelling with all attached and adjoining buildings and curtilage together with adjacent lands used by the household.

MET. On drawings, abbr. for “metal.”

meta In a racetrack, a column or monument to mark a turn.

metal-arc welding See arc welding.

metal ceiling See pressed-metal ceiling.

metal-clad cable See armored cable.

metal-clad fire door, Kalamein fire door A flush door consisting of a wood core, or stiles and rails and heat-insulated panels, covered with sheet steel.

metal curtain wall An exterior building wall which carries no roof or floor loads and consists entirely or principally of metal, or a combination of metal, glass, and other surfacing materials supported by a metal framework.

metal extrusion Same as extrusion, 1.

metal floor decking Formed sheet metal decking, 2 for structural load-carrying purposes in floor construction.

metal grating An open metal flooring for pedestrian and/or vehicular traffic, covering floor depressions or openings.

metal halide lamp, metallic-additive lamp An electric-discharge lamp in which the light is produced by the radiation from a mixture of a metallic vapor (e.g., mercury) and the products of the dissociation of halides (e.g., halides of thallium, indium, sodium, etc.).

metal lath, metal lathing, steel lathing A base for plaster fabricated: (a) by slitting metal and then stretching it to form a diamond-shaped mesh or (b) by punching and forming sheet metal. Usually classified as rib lath, diamond-mesh lath, sheet lath, or wire lath.

metal leaf A very thin sheet of metal, such as gold or silver, used in decoration or in lettering; after application, the surface may be protected against oxidation by a thin coating of shellac or lacquer.

metallic-additive lamp See metal halide lamp.

metallic area Of a wire rope, the sum of the cross-sectional areas of all of the strands of which it is composed.

metallic paint A paint or lacquer containing metal flakes which reflect light.

metallic-sheathed cable See armored cable; BX.

metallic tubing See electrical metallic tubing.

metallize To apply a coating of metal on a base material, usually by spraying the coating metal in a molten state.

metallized lamp bulb A lamp bulb having a metallic-film coating on a portion of either the inner or the outer surface to change the direction of the emitted light.

metal-molding See surface metal raceway.

metal pan See perforated metal pan.

metal primer The first coat of paint on metal; a primer, 1 coat.

metal roof covering Sheet metal or shingles, often corrugated or otherwise shaped, for application on a roof framework or on a solid roof surface; also see sheet-metal roofing.

metal sheeting Same as sheet metal.

metal siding An exterior wall siding fabricated of metal, usually aluminum.

metal structural cladding A nonload-bearing cladding for exterior walls and sloping roofs; fabricated of metal.

metal tie See tie, 1; see wall tie.

metal trim A piece of metal which protects the edges, joints, or ends of another material, such as plaster.

metal valley A velley gutter lined with metal.

metal window A metal frame, with or without a sash, which accommodates glazing.

metamer A light, 2 of the same color as another light, but of different spectral power distribution.

metamorphic rock Rock which has been altered in appearance, density, and crystalline structure (and in some cases mineral composition) by high temperature and/or high pressure; e.g., slate is a metamorphic rock derived from shale.

metatome The space between two dentils.

meter, metre (m) The International Standard unit of length; equal to 39.37 inches.

meter-candle, metre-candle See lux.

metered demand The maximum rate of the consumption of electric power or water in a building supplied by a utility.

meter rod Same as precise leveling rod.

meter stop An off-on valve in a water service pipe for stopping the flow of water to a building.

metes and bounds The boundaries, property lines, or limits of a parcel of land, defined by distances and bearings, 4.

methylated spirit A mixture of ethyl alcohol and a small amount of methyl alcohol; used industrially as a solvent for paints, lacquers, and varnishes.

methyl cellulose A granular, white flaky material which acts as a water-soluble thickener and stabilizer; used in water-based paints.

methyl chloride A gas which liquefies under compression; used as a refrigerant.

methyl ethyl ketone, MEK A strong, aromatic, flammable solvent used in paints, varnishes, and lacquers.

methyl methacrylate A tough, rigid, transparent acrylic plastic having good resistance to common solvents and acids; subject to crazing.

metoche Same as metatome.

metope The panel between the triglyphs in the Doric frieze, often carved. Also see triglyph.

metre See meter.

metric modular unit A brick whose dimensions are multiples of 10 cm.

metric sabin A unit of sound absorption equivalent to 1 sq m of perfectly absorptive surface.

metric ton Same as tonne.

metriostyle Intercolumniation in which the space between two adjacent columns is of medium distance.

meurtrière Same as gun hole.

mews 1. The royal stables in London, so called because they were built where the king’s hawks were kept; hence, a place where carriage horses are kept in cities or large towns. 2. An alley or court in which stables are or once were located.

MEZZ On drawings, abbr. for mezzanine.

mezzanine, entresol 1. A low-ceilinged story or extensive balcony, usually constructed next above the ground floor. 2. In a theater, the lowest balcony or the forward part of the first balcony. 3. A space under the stage used for the manipulation of scenery in connection with a plateau lift system.

mezzo-relievo Midway between high-relief and bas-relief.

MF Abbr. for “mill finish.”

MFG On drawings, abbr. for “manufacturing.”

MG On drawings, abbr. for “motor generator.”

MH On drawings, abbr. for manhole.

MI On drawings, abbr. for malleable iron.

MIA Abbr. for “Marble Institute of America.”

mica A naturally occurring silicate; used in paints to improve suspension and brushing properties and to improve resistance to moisture penetration; also used as a filler in plastics and in electrical and thermal insulators.

mica pellets Pellets of exfoliated vermiculite.

mica powder Very small flakes of mica (or ground mica) used in the manufacture of asphalt shingles and roofing and as a filler in paints.

microbar Same as a dyne per square centimeter.

micro crack A crack that is too fine to be seen by the naked eye but can be detected by use of electronic measurement equipment.

micron A unit of length equal to a thousandth part of a millimeter or a millionth of a meter.

microorganisms In paint technology, bacteria and fungi which are harmful to liquid paint and dry paint films. Bactericides and fungicides are added to paints to inhibit the growth of these organisms.

microphone A device which converts sound waves into essentially equivalent electric waves; the sound waves move an element in the device which generates an electric voltage.

microsand An aggregate, essentially free of clay and shale, that is sufficiently fine to pass through a No. 100 (150 µm) sieve.

microscopic Observable only with the aid of a microscope.

microstrainer A fine sieve used in the initial stage of water filtration.

microwave motion detector A device that generates a train of microwaves having a fixed frequency in a space that is to be protected. If an intruder enters and moves in the protected area, waves reflected off the intruder’s body will be of a slightly different frequency. This change in frequency is detected, thereby activating an alarm.

mid-Colonial architecture A term occasionally used for Georgian style architecture.

Middle Pointed style Same as Decorated style of Gothic architecture.

middle post 1. A king post. 2. A lock rail.

middle rail An intermediate horizontal structural member of a door between the stiles; if it contains a lock, it is called a lock rail.

middle strip In flat concrete slab framing, the slab portion which occupies the middle half of the span between columns.

midfeather 1. See parting slip. 2. A longitudinal division or partition, as a withe in a chimney or as in a cased frame.

midrail A rail approximately midway between the guardrail and platform, secured to the uprights erected along the exposed sides and ends of platforms.

mid-wall column A column which carries a part of a wall much thicker than its own diameter.

Miesian A term descriptive of the style of Ludwig Mies van der Rohe (1886–1969), a German-American architect who was a principal exponent of the International style. An outstanding example of his work is the Seagram Building in New York City (1958), designed by Mies with Philip Johnson (1906–).

migration The spreading or creeping of a sealant onto adjacent surfaces, usually to the detriment of bond.

mihrab A niche in the mosque or any religious Muslim building indicating direction of prayer toward Mecca. Focal point of decoration with dome in front.

mil, MIL 1. A unit of measure equal to a thousandth of an inch (0.0254 mm). 2. On drawings, abbr. for “military.”

mildew A fungus that grows and feeds on paint, cotton and linen fabric, etc., which are exposed to moisture; causes discoloration and decomposition of the surface.

mildewstat A chemical agent which inhibits the growth of mildew.

mild steel 1. Nearly pure iron having a very low carbon content, usually between 0.15 and 0.25%; a ductile, rust-resistant material used in boilers, tanks, enamelware, etc. 2. Same as low steel.

milestone, milepost A marker showing the distance in miles from a designated location; before the 19th century, such markers were especially helpful to those traveling between outlying communities.

mile-yard A unit equivalent to hauling one cubic yard a distance of 1 mile; used (in the US) in determining the cost of movement of excavations.

milk house Before the 19th century, a small subsidiary structure in which milk and other dairy products were stored at a lowered temperature with cooling usually provided by slowly running cold spring water or the runoff from an icehouse; typically had overhanging eaves to shade it, and double walls and ceiling filled with a thermal insulator, such as sawdust; commonly had a concrete floor to promote cleanliness and louvers for ventilation; was separated from the barn for reasons of sanitation. This term replaced by the word dairy in the 1800s; health regulations have now made such structures obsolete.

milkiness A white, semiopaque discoloration in a clear varnish film.

milk of lime A slaked lime and water solution.

milk paint Same as casein paint.

mill 1. To remove metal by a circular tool having teeth, as by use of a milling machine. 2. A machine for rolling plates, shapes, rails, etc. See bark mill, bolting mill, gristmill, sawmill, textile mill, tide mill, water mill, windmill.

mill construction See heavy timber construction.

milled lead Same as sheet lead.

milled lumber Lumber that has passed through a milling machine.

milled surface The surface obtained when metal is removed by a milling machine.

mill file A single-cut file having a rectangular cross section.

mill finish The finish on a metal sheet, bar, etc., which is produced by cold rolling or extrusion.

milliarium A column placed at intervals of one Roman mile (equivalent to 0.92 mile or 1.48 km) along a Roman road to indicate distance.

milliarium aureum A golden column erected by Augustus in 29 B.C. at the point where the principal roads of the Roman empire terminated.

millilambert A unit of luminance equal to 1/(1,000 π) candela per sq cm.

milling 1. In stonework, the processing of quarry blocks, through sawing, planing, turning, and cutting techniques, to finished stone. 2. In metalwork, the process of dressing a surface with various shapes of rotary cutters to produce a flat or grooved surface. 3. See knurling.

milling machine A machine consisting of a rotating mandrel carrying a milling cutter, and a movable table, operated by a feed screw, to which is bolted the object to be milled.

milliphot A unit of illumination equal to 1/1,000 lumen per sq cm.

mill length, random length Run-of-the-mill length of pipe, usually 16 ft to 20 ft (approx. 4.9 m to 6 m).

mill material Steel-mill products ordered explicitly for a particular job.

mill-mixed, ready-mixed Descriptive of a product that is formulated and dry-mixed by the manufacturer; only the addition of water is required at the job site.

mill practice Standardized fabrication or rolling procedures of a specific mill or of an industry, usually applicable to structural steel.

mill run Products from a mill which have not been graded or inspected.

mill scale A loose coating of oxide which forms on iron or iron products when heated.

millwork Ready-made products which are manufactured at a wood-planing mill or woodworking plant: moldings, doors, door frames, window sashes, stair work, cabinets, etc.; normally does not include flooring, ceilings, and siding.

milori blue High-quality pigment of the ferric-ferrocyanide family mixed with gypsum or barium sulfate; used in lacquers.

mimbar Same as minbar.

min, MIN 1. Abbr. for “minute.” 2. On drawings, abbr. for “minimum.”

minah See minar.

minar, minah A tower, usually a memorial monument, found esp. in India.

minaret A tall tower in, or contiguous to, a mosque with stairs leading up to one or more balconies from which the faithful are called to prayer.

minbar The pulpit in a mosque.

minchery A nunnery.

minch house A roadside inn.

mineral aggregate See aggregate.

mineral black, slate black Black pigment obtained from crushing and grinding black earth deposits, such as slate, coal, coke, or shale.

mineral dust A very finely divided mineral product, the greatest bulk of which will pass through a 74-micron (No. 200) sieve; the most common such material is pulverized limestone.

mineral fiber A fiber manufactured from glass, rock, or slag (with or without a binder) generally for use in fabricating heat insulation.

mineral fiber pad In a perforated-metal-pan acoustical ceiling assembly, the porous sound-absorptive element laid into the pan; may be enclosed in a thin, sound-transparent envelope of paper or plastic.

mineral fiber tile An acoustical tile formed of mineral or glass fiber and a binder.

mineral-filled asphalt Asphalt containing an appreciable percentage of very finely divided mineral matter which passes through a 74-micron (No. 200) sieve.

mineral filler Any finely ground mineral substance, usually inert, used as a filler.

mineral flax Fibrous asbestos; used in the manufacture of asbestos cement products.

mineral granules A natural or synthetic aggregate used to surface roofing material.

mineral-insulated cable An electric cable consisting of one or more conductors embedded in an insulating material of a highly compressed refractory mineral; has an outer sheath of continuous seamless tubular copper.

mineral pigment See earth pigment.

mineral spirit, petroleum spirit A flammable thinner having a low-aromatic hydrocarbon content obtained in petroleum distillation; widely used in paints and varnishes. Also see odorless mineral spirit.

mineral streak A dark green or brown stain in hardwoods; usually results from an injury during growth.

mineral-surfaced felt A heavy, saturated roofing felt which is coated on both sides with asphalt; the top surface is covered with particles of slate or stone; used on both sloped and flat roofs.

mineral turpentine Same as white spirit.

mineral wool A wool-like material of fine inorganic fibers such as asbestos or those made from molten rock, slag, or glass; used as loose fill or formed into blanket, batt, block, board, or slab shapes for thermal and acoustical insulation; also used as reinforcement for other materials such as insulating cements and gypsum wallboard.

minimalist architecture Architecture that follows the doctrine that the use of all decorative elements, including ornamentation and color, should be held to an absolute minimum. This tenet considers all such architectural features to be nonessential and of negative aesthetic value, thus promoting the concept attributed to Mies van der Rohe that “less is more.”

minimum acceptable pressure In a water distribution system, the lowest water pressure permitting safe, efficient, and satisfactory operation at the most hydraulically remote fixture or component in the system.

minium Naturally occurring red lead oxide; used as a pigment.

miniwarehouse A warehouse that is subdivided into a number of small, separate spaces, each with its own lock.

Minoan architecture The architecture of Bronze Age Crete, which reached its apogee between the 19th and 14th century B.C. Most important were its palaces, in which a great number of rectangular rooms of various sizes, serving different functions and connected by long labyrinthine passages, were clustered around a large central courtyard. Gate buildings with columnar porches provided access to the otherwise unfortified compounds, which were generally constructed on sloping sites, utilizing terracing and split and multilevel organization of buildings with a great number of open and enclosed stairs; light wells, air shafts, elaborate drainage and sewage systems, and flushing toilets were the engineering features. Foundation walls, piers, lintels, and thresholds were built in ashlar stone; upper walls and stories in timber framework with rubblestone masonry faced by stucco and decorated by wall paintings. Ceilings were of wood, as were the frequently used columns with their typical downward-tapering shape.

minor change A change of minor nature in the work not involving an adjustment in the contract sum or contract time, which may be effected by field order or other written order issued by the architect.

minster A monastic church; since many English cathedrals were originally associated with monasteries, the term applies to them by extension.

minstrel gallery A small balcony on the inside of a church or manor house hall, usually over the entrance.

minute One division of a module, 3.

mirador In Spanish architecture and derivatives, a lookout, whether an independent structure, a bay window, or a roof pavilion.

mirror 1. A nearly perfect reflecting surface. 2. A small oval ornament surrounded by a molding.

MISC On drawings, abbr. for “miscellaneous.”

miscellaneous storage According to NFPA standards concerning the storage of goods in a building, storage that does not exceed 12 feet (3.7 m) in height and which is incidental to another occupancy use group.

miserere, subsellium A ledge on the bottom of a hinged seat in a church; when the seat is raised, the ledge provides some support for a worshiper or choir singer who, in standing, leans against it.

misericord 1. In monastic architecture, a room or separate building where monastic rule was relaxed. 2. Same as miserere.

mismatched 1. Said of adjacent boards or veneers in which there is an absence of symmetry. 2. Said of a poorly fitting joint.

mismatch lumber Lumber or boards which are dressed and match but have edge details that do not fit properly.

mission In Spanish Colonial architecture, a church and complex of buildings usually dependent for support on a monastic order or a larger church.

Mission architecture Church and monastic architecture of Spanish religious orders, especially in the Americas in the 18th century, displaying considerable regional variation as a result of influences of skills of local laborers and the availability of construction materials; relatively unadorned in some regions but considerably more elaborate in others, often with ornamentation imitative of the elaborate and lavish Baroque or the Churrigueresque style. Mission architecture usually exhibits many of the following characteristics: thick, massive walls of adobe brick, laid with lime mortar where available, commonly with wall buttresses to provide additional stability; adobe wall surfaces usually coated with lime-and-sand stucco to reduce the effects of erosion; tamped earth floors, commonly decorated with square tile, arcaded walkways with arches usually built around the patios; commonly, multicurved gables, a belfry, bell tower, or twin bell towers; a flat roof or a low-pitched roof with shaped parapets, usually supported by round logs; thatched or tile roofs; grilles covering windows facing the street; a massive wood door at the main entrance, sometimes heavily carved or paneled, often set in an elaborately sculptured portal. Compare with Mission Revival; also see Spanish Colonial architecture.

mission dormer In Mission Revival architecture, a dormer having a multicurved shape similar to that of a mission parapet; it projects above the tiled roof.

mission parapet In Spanish Colonial architecture, a low, freestanding wall at the edge of a roof (i.e., a parapet) whose upper edge has two or more curves on each side of the uppermost point.

Mission Revival, Mission style An architectural style popular in the southwestern United States and in Florida from about 1890 to 1930 and beyond; suggestive or imitative of the earlier Mission architecture, although usually much simpler because of the absence of sculptured ornamentation; compare with Spanish Colonial Revival. Buildings in this style are usually characterized by: stucco-finished exterior walls, occasionally with terracotta ornamentation; balconies or balconets; semicircular arches; a roof supported by massive piers with broad arches between them, forming arcaded walkways; multicurved gables; a low-pitched red mission-tile roof; often a hipped roof; open eaves having exposed rafters and a significant overhang; roof ridges topped with a red-tiled protective cap; commonly, dormers; tile-faced bell towers; roof drainage provided by waterspouts that pierce the parapets; typically, double-hung rectangular windows; a main entry door often located within a recessed porch.

mission tile 1. A red-clay roofing tile, approximately semicylindrical in shape; laid in courses, with adjacent tiles having their convex side alternately up and down; also called Spanish tile. 2. Same as pantile, 2.

mist coat A sprayed coat of very dilute paint.

miter, mitre The oblique surface forming the beveled end or edge of a piece where a miter joint is made.

miter arch, mitre arch Two straight blocks of stone set diagonally over an opening, the upper ends resting against each other.

miter bevel A piece of material, such as wood, usually cut at a bevel, 1 of 45°, used with a similarly beveled piece to form a right-angled joint.

miter block In joinery, a wood block arranged for sawing pieces at an angle of 45°.

miter board, miter shoot A board on which material to be planed is laid; guides or stops hold the material at the prescribed angle so that the ends of the miters can be planed at the correct angle.

miter box A device for guiding a handsaw at the proper angle in making a miter joint; often a narrow wooden box having a bottom and two sides in which kerfs are cut (usually at an angle of 45°) for guiding the saw.

miter brad Same as corrugated fastener.

miter cap, mitre cap A shaped wood block, supported by the newel post, which receives the mitered handrail.

miter clamp, miter cramp A clamp used to hold together a miter joint during gluing.

miter cramp See miter clamp.

miter cut Any oblique cut across two pieces of board or molding, so that when joined they form an angle.

miter dovetail See secret dovetail.

mitered-and-cut string Same as cut-and-mitered string.

mitered closer A brick closer cut at an oblique angle.

mitered fitting A fitting especially manufactured for use with beveled pipe.

mitered hip A close-cut hip.

mitered tile A piece of tile that is cut at the appropriate angle that will finish upright work; at the corners of dormers.

mitered valley A valley which is close-cut.

miter ending The end of a member having an angular, dovetailed, or square member which is designed to fit into an adjacent matching member so as to provide a continuous profile at the joint.

miter gauge A gauge for determining the angle of a miter.

mitering machine A machine for sawing or cutting the ends of pieces to be joined to a true angle of 45°, in order that they may be united by a miter joint, or for cutting the pieces to any desired angle to make a bevel joint.

miter joint A joint between two members at an angle to each other; each member is cut at an angle equal to half the angle of the junction; usually the members are at right angles to each other.

miter knee The miter joint between the horizontal handrail at a stair landing and the adjacent angled handrail of the descending stairs.

miter plane A carpenter’s plane generally used for preparing miter joints or butt joints.

miter post A meeting post.

miter rod A flat steel plate having one end cut at a 45° angle; used by plasterers in finishing reentrant corners.

miter saw See tenon saw.

miter shoot See miter board.

miter square 1. In carpentry, a square with a handle having one edge with a bevel at an angle of 45°; used for laying out miter joints. 2. A bevel square with a blade having a fixed angle of 45° for marking miters prior to cutting.

miter valve A valve having a disk that fits in a seat at a 45° angle to the axis of the valve.

mitre British variant of miter.

mix A ready-mixed batch of concrete, plaster, or mortar.

MIX. On drawings, abbr. for “mixture.”

mix design Same as proportioning.

mixed arch A three- or four-centered arch; a composite arch.

mixed garden wall bond In brickwork, a bond similar to English garden wall bond, except that the course of headers is replaced by one consisting of alternate headers and stretchers.

mixed glue A ready-mixed synthetic resin glue.

mixed-grained lumber Edge-grained and flat-grained lumber in any combination.

mixed-in-place pile A soil-cement pile, formed in place by forcing a grout mixture through a hollow shaft into the ground where it is mixed with in-place soil.

mixed occupancy In a building, two or more classes of occupancy so intermingled that separate safeguards for each class are impractical; the building construction, fire protection, exit facilities, and other safeguards meet the requirements for the most hazardous occupancy unless otherwise specified.

mixed use 1. Descriptive of a district that has been zoned to permit more than a single use, for example, commercial and residential. 2. Descriptive of a building that has more than one use.

mixer A machine employed for blending the constituents of concrete, grout, mortar, or paint.

mixer efficiency The adequacy of a mixer in rendering a homogeneous product within a stated period; determinable by testing samples, which are extracted from various portions of a freshly mixed batch, for differences in physical properties.

mixer truck See truck mixer.

mixing box 1. A device used to reduce the air velocity in the duct of a medium- or high-pressure, high-velocity HVAC system; incorporates a valve which controls the volume of flow for distribution of air within a room and for mixing hot and cold air. 2. See dual-duct system.

mixing cycle In mixing concrete in a batch mixer, the time taken for a complete cycle, i.e., the elapsed time between successive discharges of the mixer.

mixing plant See batch plant.

mixing speed In mixing a batch of concrete, the rate of rotation of a mixer drum or of the paddles in an open-top, pan, or trough mixer, expressed in rpm or in feet per minute (or meters per minute) of a point on the circumference of the drum at its maximum diameter.

mixing time The period of time during which the constituents of a batch of concrete are mixed in a fixer.

mixing valve A valve which mixes liquids, by either automatic or manual regulation.

mixing varnish A varnish which is added to a pigmented paint to increase its gloss or improve its sealing properties.

mixing water The water in freshly mixed sand-cement grout, mortar, or concrete, exclusive of any previously absorbed by the aggregate.

mix proportion In a given concrete mixture, the ratio of cement to sand to gravel, in terms of either dry, loose volume or dry weight.

Mixtec architecture A type of Mesoamerican architecture, circa 1000 A.D., in the state of Oaxaca, Mexico; usually characterized by great mass, use of interior stone columns, and emphasis on horizontal lines; minutely detailed fretwork on paneled friezes; use of scapulary tablets on building façades.

mixture 1. The assembled, blended, commingled ingredients of mortar, concrete, or the like. 2. The proportions for their assembly.

MK On drawings, abbr. for “mark.”

ML On drawings, abbr. for “material list.”

mldg, Mldg Abbr. for “molding.”

MLMA Abbr. for “Metal Lath Manufacturers Association.”

mm Abbr. for “millimeter.”

MN On drawings, abbr. for “main.”

MO On drawings, abbr. for “month.”

moat A broad, deep trench surrounding the ramparts of a town or fortress; usually filled with water.

mobile form Same as slipform.

mobile scaffold A portable rolling scaffold supported by casters.

mock-up A model of an object in the course of design, as a section of a window or its parts; built to scale or at full size, for purposes of studying construction details, judging appearance, and/or testing performance.

MOD On drawings, abbr. for “model.”

mode See architectural mode.

model 1. A representation or reproduction, usually at small scale, for purposes of study or to illustrate construction. 2. A pattern of an item to be reproduced, often in quantity.

model code (US) A proposed building code that is written and published by building-official associations (e.g., BOCA, ICBO, and SBCC); available for adoption by states, counties, and municipalities.

modeling, Brit. modelling Forming or shaping a clay or plaster surface.

moderately hydraulic lime A putty that sets slowly, for a period up to one month.

Modern architecture A loose term applied since the late 19th century to buildings in a variety of styles, in which emphasis is placed on functionalism, rationalism, and current methods of construction, in contrast with architectural styles based on historical precedents and traditional methods of building. This category often includes Art Deco, Art Moderne, Bauhaus, Contemporary style, International style, Organic architecture, Streamline Moderne.

Moderne An imprecise term occasionally applied to Art Moderne, PWA Moderne, Streamline Moderne, and Art Deco.

Moderne Style Same as Style Moderne; also see Art Deco.

Modernismo The Spanish, particularly Catalan, version of Art Nouveau.

Modernistic style See Art Deco and Art Moderne.

modernize To adapt a building or structure to current conditions, tastes, or usage, usually by remodeling.

Modern style An imprecise term that often includes Contemporary style and Shed style.

modification 1. A written amendment to the contract document signed by both parties. 2. A change order. 3. A written or graphic interpretation issued by the architect. 4. A written order for a minor change in the work, 1 issued by the architect.

modified asphalt An asphalt that has been modified by the addition of a synthetic resin or rosin ester.

modified portland cement, type II portland cement A cement used in general construction where moderate heat of hydration is required.

modillion A horizontal bracket or console, usually in the form of a scroll with acanthus, supporting the corona under a cornice. If in the form of a plain block, it is a block modillion or uncut modillion. Found in Corinthian, Composite, and, less frequently, Roman Ionic orders.

modillion block See modillion.

modillion cornice A cornice supported by a series of modillions, often found in Composite and Corinthian orders.

modular construction 1. Construction in which a selected unit or module, such as a box or other subcomponent, is used repeatedly in the aggregate construction. 2. A system of construction employing large, prefabricated, mass-produced, partially preassembled sections or modules which are subsequently put together in the field.

modular dwelling A manufactured home consisting completely or in part of module, 4.

modular masonry unit A brick or block whose nominal dimensions are based on a 4-in. (10.16 cm) module.

modular ratio The ratio of the modulus of elasticity of steel to that of concrete.

modular system, modular design A method of designing or constructing buildings and equipment in which modules are widely used.

module 1. A distinct component forming part of an ordered system. 2. A repetitive dimensional or functional unit used in planning, recording, or constructing buildings or other structures. 3. A standard, usually of length, by which the proportions of a building are determined. 4. A unit of a building structure which is based on a standard pattern of standard dimensions.

modulus of elasticity In an elastic material which has been subject to strain below its elastic limit, the ratio of the unit stress to the corresponding unit strain.

modulus of resilience The amount of elastic energy absorbed by a unit volume of a material when it is loaded to its elastic limit in tension.

modulus of rigidity, modulus of shear In an elastic material which has been subjected to stress, the ratio of the shearing stress to the shearing strain.

modulus of rupture A measure of the ultimate load-carrying capacity of a beam; equal to the ratio of the bending moment at rupture to the section modulus of the beam.

modulus of subgrade reaction Same as coefficient of subgrade reaction.

modulus of toughness The amount of energy per unit volume which is absorbed by a structural material when subject to shock or impact, up to the point of fracture.

moellon Stone rubble used as filling between the facing walls of a structure.

Mogen David See Star of David.

Mogul architecture The later phase of Indian Islamic architecture, named after the Mogul dynasty (1526–1707), typified by monumental palaces and mosques and detailed decorative work. The Taj Mahal is the most famous example.

mogul base A large, screw-in type of base for an incandescent lamp of 300 watts or higher.

Mohammedan architecture See Muslim architecture, Islamic architecture.

Mohs’ scale A scale which rates the scratch hardness of a mineral on a scale of 1 (talc) to 10 (diamond).

moist room A room in which the atmosphere is maintained at a selected temperature, usually 73.4°F (23°C), with a relative humidity of at least 98%, for the purpose of curing and storing cementitious test specimens.

moisture barrier 1. A vapor barrier. 2. A damp course.

moisture content 1. The weight of water, usually expressed as a percentage of the total dry weight of a material. 2. The weight of water in a given soil mass.

moisture equilibrium See equilibrium moisture content.

moisture expansion 1. See bulking. 2. An increase in dimension or bulk volume of a material or manufactured article caused by the absorption of water or water vapor.

moisture gradient The difference in moisture content between the inside and outside of a piece of wood.

moisture migration Same as moisture movement.

moisture movement 1. The process by which moisture moves through a porous medium, such as a wall construction, as a result of differences in vapor pressure. 2. The effects of such movement on the dimensions of a material such as concrete, mortar, cement paste, or rock.

moistureproofing The application of a moisture barrier.

MOL Abbr. for maximum overall length.

mold, mould 1. A concave and/or convex form from which castings or pressings are replicated. 2. A template or pattern. 3. Same as molding.

molded brick 1. A specially shaped brick, usually for decorative work. 2. Ordinary brick which is neither cut with a wire nor pressed.

molded-case circuit breaker A relatively light, fast-acting electrical circuit breaker assembled as an integral unit in a supporting and enclosing housing of molded insulating material.

molded insulation A thermal insulation material that is premolded to fit the surface contours of pipes, pipe fittings, valves, etc.

molded plastic skylight A skylight molded of transparent or translucent plastic, which allows the passage of light to the space below.

molded plywood Plywood formed and cured into a curved shape.

molding A member of construction or decoration so treated as to introduce varieties of outline or contour in edges or surfaces, whether on projections or cavities, as on cornices, capitals, bases, door and window jambs and heads, etc.; may be of any building material, but almost all derive at least in part from wood prototypes (as those in classical architecture) or stone prototypes (as those in Gothic architecture). Moldings are generally divided into three categories; rectilinear, curved, and composite-curved. Also called a mold. For special definitions and illustrations, see applied molding, beadmolding, bead-and-reel molding, bolection molding, cyma, dripmolding, egg-and-dart molding, half-round molding, head molding, hip molding, hood molding, Italian molding, label molding, laid-on molding, ogee, ovolo molding, planted molding, quarter-round molding, rope molding, scotia, stop molding, struck molding, sunk molding, tongue-and-dart molding, treacle molding, weather molding.

sections of classical moldings: A, cavetto; B, congé; D, cyma recta; E, quarter round; F, ovolo; G, echinus; H, cyma reversa; I, half round; J, torus; K, thumb; L, half hollow; M, fillet; N, bead; O, scotia; P, cavetto; Q, scape; R, cyma recta; S, cyma reversa; T, ovolo

molding machine A high-speed machine for planing, shaping, and cutting moldings.

molding pattern See WP-series molding pattern.

molding plastic A partially polymerized resin, usually in powdered form, which is molded under heat and pressure; often filler materials and pigments are added.

molding powder See molding plastic.

mold stone The jambstone of a door or window.

molecular sieve An adsorbent composed of porous aluminosilicates with pores of uniform molecular dimensions which will selectively absorb molecules of the substance to be gathered.

mole drain A subsurface channel for draining water.

moler brick 1. An insulation brick made from moler earth, a type of diatomaceous material. 2. A brick made from any diatomaceous earth, i.e., any diatomite.

molybdate orange Bright orange pigment consisting of mixed crystals of lead chromate, lead molybdate, and lead sulfate; used in paint because of its high opacity.

moment The property by which a force tends to cause a body, to which it is applied, to rotate about a point or line; equal in magnitude to the product of the force and the perpendicular distance of the point from the line of action of the force.

moment connection A rigid or semi-rigid connection between columns and girders.

moment of inertia Of a body around an axis, the sum of the products obtained by multiplying each element of mass by the square of its distance from the axis.

momentum Of a moving body, the product of the mass of the body and its velocity.

monastery A building complex of a monastic order.

monial Same as mullion.

monitor, monitor roof A raised section of a roof, usually straddling a ridge; has openings, louvers, or windows along the sides to admit light or air.

monitor skylight A skylight placed in a raised section of a roof, often straddling a ridge.

monk bond Similar to Flemish bond but with two stretchers instead of one between each header.

monkeytail The vertical scroll at the bottom of a handrail of a stairway.

monkeytail bolt An extension flush bolt.

monkey wrench A wrench having one jaw fixed and the other jaw (which is adjusted by a screw) movable.

monolith An architectural member (as an obelisk, the shaft of a column, etc.) consisting of a single stone.

monolithic 1. Shaped from a single block of stone, as a monolithic column. 2. Composed of monoliths. 3. Characterized by massiveness and complete uniformity. 4. Said of concrete which is cast in a single piece. 5. Said of a concrete pavement or floor whose surface layer is formed integrally with the slab below.

monolithic concrete Reinforced concrete cast with no joints other than construction joints.

monolithic pour A pour of concrete, all at a single time. Also called a one-pour system. Contrast with two-pour system.

monolithic screed Screed, 4 laid in a single layer without joints.

monolithic surface treatment, dry shake The treatment of the surface of unformed concrete by sprinkling a mixture of dry cement and sand on it after the water has mostly disappeared from the surface, following the strike-off; it is then worked in by floating.

monolithic terrazzo A terrazzo topping which has been applied directly on a specially prepared concrete substrate; no underbed is used.

mono lock See preassembled lock.

monomer An organic liquid having a relatively low molecular weight which reacts with itself (or other compounds of low molecular weight) to create a solid polymer.

mono-pitched roof A pitched roof having a single slope.

monopteron In Greek architecture, a circular peripteral building, as a temple, having only a single row of columns.

monostyle 1. Having but a single shaft; applied to medieval pillars. 2. Having the same style of architecture throughout.

monotower crane Same as tower crane.

monotriglyphic In the Doric order, having one triglyph over the space between two columns.

monstrance See ostensory.

montant That part of a framed stile which is in contact with the rail.

Monterey style, Monterey Revival An architectural style that came into existence in Monterey, California, between about 1835 and 1840; typically, a two-story house with a full-façade balcony supported by plain wood posts and enclosed by wood railings. A modified version of this style was revived from about 1920 to 1960, combining Spanish Colonial architecture with some elements of early New England colonial architecture; in this 20th-century version, the balcony is typically cantilevered rather than supported by wood columns from ground level, as in the earlier Monterey style. Nineteenth-century houses in this style usually were characterized by: thick whitewashed adobe walls; a low-pitched gable roof or hipped roof with its ridge parallel to the façade, usually covered with hand-split wood shingles, but sometimes with tiles; occasionally a decorative chimney cap or chimney hood; double-hung wood-frame windows with mullions; often, window shutters; occasionally, full-length windows opening onto the balcony; a relatively simple paneled entry door. Doors in 20th-century houses in this style are often imitative of those found in Colonial Revival architecture, including paneling, a fanlight over the door and sidelights flanking the door; occasionally, some elements of Greek Revival are included in the wood trim around doors and windows.

montmorillonite One of the common clay minerals which typically swells upon wetting and becomes soft and greasy.

monument 1. A permanent natural or artificial object marking the corners and boundaries of real property or establishing the location of a triangulation or other important survey station. 2. A stone, pillar, megalith, structure, building, or the like, erected in memory of the dead, an event, or an action.

monumental stone A dimension stone of adequate size and quality for use in carving a monument or a memorial.

moon gate In traditional Chinese architecture, a circular opening that provides a passageway through a wall.

Moorish arch Same as horseshoe arch.

Moorish architecture The Islamic architecture of North Africa and the regions of Spain once under Islamic domination.

Moorish Revival A rarely used mode of Exotic Revival architecture from about 1845 to 1890. Usually characterized by the use of horseshoe arches, multifoil arches, and window tracery.

moot hall A place of public assembly; a hall for meeting, debate, or judgment; a town hall.

mop-and-flop A roofing procedure in which roofing elements (such as felt plies or cap sheets) are initially placed upside down adjacent to their ultimate locations on the substrate; then they are coated with adhesive, turned over, and adhered to the substrate.

mopboard A baseboard.

mopping Applying hot bitumen with a mop or mechanical applicator on the felt of a built-up roof membrane, on a roof-deck, or the like.

mop plate A narrow plate fixed to the bottom of a door for protection against soiling from a mop; similar to a kickplate.

mop sink A type of sink having a deep basin, usually used by janitors.

mopstick handrail A handrail having a circular cross section except for a small flat on the underside.

Moresque architecture Same as Moorish architecture.

morgue, mortuary A room or building for the holding and/or identification of dead bodies prior to burial or cremation.

Mormon thatched-roof shed Same as jacal, 1.

morning room A family, or private, sitting room, usually sunlit early in the day.

mortar, mortar mix A plastic mixture of cementitious materials (such as plaster, cement, or lime) with water and a fine aggregate (such as sand); can be troweled in the plastic state; hardens in place. When used in masonry construction, the mixture may contain masonry cement or ordinary hydraulic cement with lime (and often other admixtures) to increase its plasticity and durability. Also see clay-and-hair mortar, gypsum mortar, lime mortar.

mortar aggregate An aggregate consisting of natural or manufactured sand.

mortar bed 1. A mortar box. 2. A thick layer of mortar used to seat a structural member.

mortarboard, fat board, spot board A board, usually set on legs to form a table, used to mix lime putty and gauging plaster.

mortar box, mortar bed A shallow, trough-like box in which mortar or plaster is mixed.

mortar brick A type of brick used primarily in the 18th and 19th centuries; usually consisted of a mixture of sand and lime, to which water was added; then molded into bricks and allowed to harden in the open air; primarily used in regions where clay for making a better grade of bricks was unavailable.

mortar classification A system of classifying mortar for brickwork numerically, from 1 to 5, 1 being the strongest and 5 the weakest.

mortar cube test A test of the compressive strength of a material; a sample is formed into a cube, dried according to a standard procedure, and then crushed.

mortar fillet Same as cement fillet.

mortar joint See masonry joint.

mortar mill A mixing and stirring machine for combining lime, sand, and other materials to make mortar.

mortar mix See mortar.

mortar tray A template designed to facilitate the laying of two ribs of mortar in conjunction with V-brick.

mortgage A loan in which property is used as security for the debt.

mortgagee The lender from whom a mortgage is obtained.

mortgage lien A charge against property as security for the payment of a loan.

mortgagor The borrower who obtains a mortgage.

mortice British variant of mortise.

mortise A hole, cavity, notch, slot, or recess cut into a timber or piece of other material; usually receives a tenon, but also has other purposes, as to receive a lock.

mortise-and-tenon joint, mortise joint A joint between two wood members that is formed by fitting a tenon at the end of the one member into a mortise in the other member; the mortise and the tenon are usually cut or shaped with a mallet and chisel. After fitting the tenon into the mortise, a hole is drilled through them with an auger; then a wooden peg (treenail) is driven into the hole to secure the joint. Also called a mortise-and-pegged joint.

mortise bolt A door bolt designed to be mortised into a door rather than applied to its surface.

mortise chisel, framing chisel, heading chisel, socket chisel A steel chisel for woodworking; has a heavy body with a socket shank; esp. used for cutting mortises.

mortised astragal On a door having two leaves, a two-piece astragal having one part recessed in the edge of each door.

mortise gauge A tool (similar to a marking gauge) having two scribes for marking parallel lines; can be adjusted to the required distances from a working edge in preparing mortises or tenons.

mortise joint See mortise-and-tenon joint.

mortise latch A mortise lock.

mortise lock A lock designed to be installed in a mortise rather than applied to a door’s surface.

mortise machine A machine which cuts square or rectangular holes, usually with a chisel, or circular holes with a circular cutting bit.

mortise pin A pin which locks a mortise-and-tenon joint by being driven either through the extended tenon or through both the mortise and the tenon.

mortise preparation On a door or doorframe, the drilling, tapping, and reinforcing for hardware which is to be mortised into it.

mortuary See morgue.

mortuary temple A temple for offerings and worship of a deceased person, usually a deified king, as distinguished from a cult temple.

mosaic 1. A pattern formed by inlaying small pieces of stone, tile, glass, or enamel into a cement, mortar, or plaster matrix. 2. A form of surface decoration, similar to marquetry, but usually employing small pieces or bits of wood to create an inlaid design.

Moslem architecture See Muslim architecture.

mosque A Muslim house of worship.

MOT On drawings, abbr. for “motor.”

motel A roadside building or group of buildings which contains hotel and parking accommodations primarily for transient motorists, often with individual exterior entrances to each room.

motif A principal repeated element in an ornamental design.

motion detector A device to detect intrusion within an area to be protected. The device radiates waves (electromagnetic or ultrasonic, at a fixed frequency) that are reflected back to the device. If an intruder moves within the protected space, a change in frequency results which is detected and which activates an alarm.

motor A machine which converts electric power into mechanical power by means of a rotating shaft.

motor branch circuit A branch circuit which supplies electric power to one or more motors and their associated controllers.

motor-circuit switch A switch intended for use in an electric-motor branch circuit; rated in horsepower and capable of interrupting the maximum operating overload current of a motor of the same rating at the rated voltage.

motor controller A controller which governs the power delivered to a motor (or group of motors).

motor-generator set A machine that consists of a motor which is mechanically coupled to an electric generator.

motor grader A dirt-moving machine for leveling and planing the surface to fine tolerances by means of a blade (or moldboard) than can be set and held at precise slope and elevation. Controls at the operator’s station raise and lower, turn, and tilt the moldboard.

motorized buggy cart A type of power-driven wheelbarrow.

motor starter A motor controller used only for connecting and disconnecting a motor.

motte In medieval times, a high, defensive mound of earth surmounted by a timber stockade and tower, and surrounded by a ditch.

motte-and-bailey A motte that is adjacent to, or surrounded by a bailey; the open area within a medieval fortification.

mottle 1. The pattern or arrangement of spots and cloudings forming a mottled surface, esp. in marble, or in wood veneer as a result of unusual variation in fiber growth or fiber arrangement. Also see fiddleback, quilted figure, blister figure. 2. See mottling.

mottler In painting, a brush having a flat thick shape; used for graining and marbling.

mottling Spotty round marks which appear as a defect in a sprayed film of paint.

moucharaby See meshrebeeyeh.

mouchette In 14th cent. Gothic tracery and derivatives, a typical small motif, pointed, elongated, and bounded by elliptical and ogee curves; a dagger motif with a curved axis.

mould, moulding British variants of mold, molding.

mouse, duck A lead weight on a string; used to pull a sash cord over a sash pulley, to clear a blocked pipe, etc.

mouse-tooth pattern, mouse-tooth finish See tumbling course and straight-line gable.

movable form In the placement of concrete, a formwork which has been so sized in its manufacture or construction as to be suitable for repetitive use in a series of pours.

movable partition A demountable partition.

movement In wood, same as working.

movement joint Same as expansion joint, 1.

moving ramp A continuously moving system on which passengers stand, to be carried along a horizontal plane or up an inclined plane.

moving staircase, moving stairway See escalator.

moving walkway A continuously moving passenger-carrying device on which passengers stand or walk; the passenger-carrying surface remains parallel to its direction of motion and is uninterrupted.

mow The loft in a barn for storage of hay.

Mozarabic architecture Northern Spanish architecture built after the 9th cent. by Christian refugees from Moorish domination, characterized by the horseshoe arch and other Moorish features.

Mozarabic style A style of architecture used by Christians in Spain from about the 9th to the 16th century, when Spain was under Moorish domination.

mpl Abbr. for maple.

MR Abbr. for mill run.

M-roof A roof formed by joining two parallel gable roofs, creating a valley between them, resembling the capital letter M in section.

MRT Abbr. for “mean radiant temperature.”

MRTR On drawings, abbr. for mortar.

MSDS Abb. for “Material Safety Data Sheet,” used by OSHA for construction materials.

mucilage 1. An adhesive prepared from a gum and water. 2. A liquid adhesive which has low bonding strength.

muck 1. An organic soil of very soft consistency; also called muck soil. 2. Material to be excavated; clay, dirt, loam, stone, etc. 3. The material so excavated.

muck soil Same as muck, 1.

mud A mixture of soil with sufficient water to make it soft.

mud-and-sticks chimney Same as clay-and-sticks chimney.

mud brick A term occasionally used for adobe that has been shaped in a brick form and then sun-dried.

mud-capping The blasting of a boulder by placing a quantity of explosives against it without confining the explosives in a drill hole.

Mudejar architecture A Spanish style created by Moors under Christian domination in the 13th and 14th cent., but retaining Islamic elements such as the horseshoe arch.

mudflow Movement of soft weak soil having the consistency of mud.

mud house Any primitive dwelling having walls of unbaked earth; often constructed of molded sun-dried blocks of mud usually mixed with straw, manure, or other material to provide increased mechanical strength.

mud-jacking A process of raising a concrete slab on ground where it has settled or been depressed; a hole is drilled through the slab, then a mixture of mud and cement is pumped beneath the slab under pressure, thereby raising it.

mud plaster A plaster that is usually a mixture of heavy clay and water, often containing chopped straw or manure to improve its mechanical strength when dry.

mud room A small entry area in a house where muddy footwear and wet outer clothing may be removed and stored temporarily.

mud sill The lowest horizontal timber at the base of a timber-framed building, usually laid directly on the ground; used to distribute concentrated loads.

mud slab A layer of concrete, 2 in. (5 cm) to 6 in. (15 cm) thick, below a structural concrete floor or footing over soft, wet soil.

mud wall A wall usually constructed of a mixture of clay and a binder such as chopped straw; often, gravel is added.

muff glass Window glass, made by a now obsolete technique. A glass cylinder was blown; but before it cooled, it was sliced lengthwise and unrolled into a flat piece from which the panes were cut.

muffle 1. A material used to build up the core of a large plaster molding. 2. To deaden sound.

muffler See sound attenuator.

Mughal architecture See Mogul architecture.

mulch Material such as leaves, hay, straw, or the like, spread over the surface of the ground to protect the roots of newly planted shrubs or trees, of tender plants, etc., from the sun or from the cold.

mullion A vertical member separating (and often supporting) windows, doors, or panels set in series. Also see door mullion.

mullion cover A loose piece of metal trim which screws or snaps in place on the interior side of the mullion of a window.

MULT On drawings, abbr. for “multiple.”

multibag packer See carousel packer and linear packer.

multi-blade damper A damper, 1 through which the quantity of airflow is controlled by means of a number of blades linked together mechanically.

multicentered arch An arch having a shape composed of a series of circular arcs with different radii, giving an approximation to an ellipse. These arcs are symmetrically disposed about a vertical axis and occur in odd numbers.

multicolored brick See rustic brick.

multicolor finish A speckled paint finish containing small individual colored particles.

multiconductor cable An assemblage of several electrical conductors having a common outer jacket.

multicurved gable A gable having an outline containing two or more curves on each side of a central ridge; for example, see Flemish gable.

multicurved parapet At the edge of a roof, a freestanding wall whose outline contains several curves on its upper surface, as in a mission parapet.

multi-element prestressing Prestressing of reinforced concrete which is accomplished by stressing an assembly of several individual structural elements to produce one integrated structural member.

multifamily dwelling A residential building containing more than two dwelling units.

multifoil Having more than five foils, lobes, or arcuate divisions.

multifolding door A door composed of large panels hung on a ceiling track; when the door is open, the panels stack against each other and are housed in a relatively small space.

multifuel burner A burner which can be fed by more than one type of fuel, used either separately or simultaneously.

multimedia filter In a water supply system, a bed-type filter containing several different filtration media (e.g., coal, sand, and garnet).

multi-outlet assembly A metallic or nonmetallic assembly used in electric wiring; a type of surface-mounted or flush raceway designed to hold conductors and attachment plug receptacles; assembled in the field or at the factory.

multiple dwelling A building for residential use which houses several separate family units, usually three or more.

multiple echo See flutter echo.

multiple-family Said of a building in which more than two families or households live independently of each other and do cooking within their own living quarters.

multiple-folding rule A folding rule up to 8 ft long used where precision accuracy is not required.

multiple frame A framework of beams and columns extending over more than one bay in a horizontal direction.

multiple glazing Glazing comprised of more two or more sheets of glass with space between them, e.g., see double glazing.

multiple hoistway A hoistway for more than a single elevator or dumbwaiter.

multiple-layer adhesive A film-type adhesive inserted between dissimilar materials in order to bond them together; often a different type of adhesive is used on each side of the film.

multiple-layer weld A weld in which more than one pass or deposit of filler metal is required to obtain the required dimensions of the weld.

multiple of direct personnel expense A method of compensation for professional services based on the direct expense of professional and technical personnel, including cost of salaries and mandatory and customary benefits, multiplied by an agreed factor.

multiple prime contract A contract in which more than one primary contractor has been retained to work on the same project.

multiple-window operator See mechanical operator.

multiplier The factor by which an architect’s direct personnel expense is multiplied to determine compensation for his professional services or designated portions thereof.

multi-ply construction Laminated construction having more than three plies. Also see balanced construction.

multistage stressing The prestressing of reinforced concrete performed in stages as the construction progresses.

multistory Having several stories, usually more than five.

multistory frame, skeleton construction A building framework of more than one story in which loads are carried to the ground by a system of beams and columns.

multi-unit wall A masonry wall composed of two or more withes.

multivallate A fort on a hill that is protected by three or more concentric ditches and embankments.

multiway deflection The deflection of air, from an air outlet, in several directions, usually at 90° to each other.

multizone system An air-conditioning system which is capable of handling several individually controlled zones simultaneously.

municipality A town, city, or district possessing corporate jurisdiction.

municipal planning See city planning and community planning.

muniment house, (Brit.) muniment room A secure structure or area for storing and displaying important documents, official seals, etc.

munnion 1. A mullion. 2. A muntin.

muntin 1. A secondary framing member to hold panes within a window, window wall, or glazed door; also called a glazing bar, sash bar, window bar, or division bar. 2. An intermediate vertical member that divides the panels of a door. Also see curved muntin.

munton Same as mullion.

Muntz metal, malleable brass, (Brit.) yellow metal A copper-zinc metal alloy having 60% copper and 40% zinc; used in castings and in extruded, rolled, and stamped products.

muqarnas, honeycomb work, stalactite work An original Islamic design involving various combinations of three-dimensional shapes, corbeling, etc.

mural 1. Pertaining to a wall. 2. A mural painting, decorative or figurative.

mural arch An arch in a wall which was constructed in the plane of the meridian; used for attachment of astronomical instruments in the Middle Ages.

mural tower In a medieval fortification, one of a number of towers built along a curtain wall, 2.

murder hole An opening in an overhanging medieval defensive structure through which boiling water, boiling oil, or rocks could be dropped on an attacker; also called a machicolation.

murtrière Same as murder hole.

murus A wall of stone or brick, built as a defense and fortification around an ancient Roman town. Also see paries.

murus coctilis A wall built of bricks that have been hardened in a kiln at an especially elevated temperature.

museum An institution for the assembly and public display of any kind of collection, esp. one of rare and/or educational value.

mushrabiya See meshrebeeyeh.

mushrebeeyeh Same as meshrebeeyeh.

mushroom column In reinforced concrete construction, a structural column, suggestive of a mushroom shape, that flares at the top to counteract sheering stresses.

mushroom construction A type of flat slab construction which utilizes column capitals and drop panels.

mushroom light A lighting fixture having light bulbs that are located on the underside of a mushroom-like fixture set at ground level; especially used to illuminate a path so that bulbs are not visible to a person walking along the path.

mushy concrete A concrete of relatively fluid consistency; used where mobility after initial placement is important, as between narrowly spaced forms or where reinforcement is closely spaced.

musicians’ gallery At the west end of a church in Europe during the 18th century, a gallery on which villagers played church music.

musivum Same as opus musivum.

musket-stock post A principal vertical structural support, in an early timber-framed house, having the shape of an inverted musket stock; the additional thickness at the top provides an added bearing surface to support the imposed load.

Muslim architecture, Muhammadan architecture, Saracenic architecture Architecture developed from the 7th to the 16th cent. A.D., in the wake of the Muhammadan conquests of Syria and Egypt, Mesopotamia and Iran, North Africa and Spain, Central Asia and India, countries from which it absorbed in turn elements of art and architecture. A new building type was developed from the Christian basilica—the multiaisled, arcaded, columnar, or pillared mosque; a new type of domed mosque, tomb, or madrasah from the vaulted, centrally organized Byzantine and Sassanian structures. Uses many variations of basic architectural elements; pointed, horseshoe, “Persian,” multifoil, and interlacing arches; bulbous, ribbed, conical, and melon domes; tunnel, cross-rib, and stalactite vaults; a wide variety of crenelations. Surfaces are covered by abundant geometric, floral, and calligraphic decorations executed in stone, brick, stucco, wood, and glazed tile.

mute A mortised rubber silencer for a door.

mutule A sloping flat block on the soffit of the Doric cornice, usually decorated with rows of six guttae each; occurs over each triglyph and each metope of the frieze.

Mycenaean architecture Architecture of the heroic age in southern Greece from the 17th to 13th century B.C. Exemplified in the earliest phase by shaft graves cut into the sloping rock, with sidewalls of stone masonry and a timber roof; in the middle period by monumental beehive tombs constructed of superimposed layers of enormous stone blocks progressively projecting to create a parabolic corbeled vault, with a stone-faced, inclined access passage leading to the entrance composed of upward-slanting jambs and a heavy stone lintel supporting a characteristic Mycenaean relief triangle; in the late period by fortified palaces having Cyclopean walls, underground passages with corbeled vaults, postern gates, and cisterns, laid out on an irregular ground plan, with distinctive propylaea, one or more unconnected columnar halls with porches facing individual courts, and long corridors linking auxiliary and storage rooms.