Exterior wallsIn this chapter you will find discussions regarding the provisions as set forth by the International Building Code regarding the following items:
Exterior walls
Exterior wall coverings
Exterior wall openings
Exterior windows and doors
Architectural trim
Balconies and similar projections
Bay and oriel windows.
This section applies to exterior walls, wall coverings, and components of such. All exterior walls need to be weather protected with a weather-resistant exterior wall envelope.
Exterior wall envelope: A system or assembly of exterior wall components, including exterior wall finish materials, that provides protection of the building structural members, including framing and sheathing material and conditioned interior space, from the detrimental effects of the exterior environment. |
An exterior wall envelope must include flashing and must be designed and constructed in such a manner so that an accumulation of water within the wall assembly is prevented. The envelope must provide a water-resistive barrier behind the exterior veneer, and a way for any water that enters the assembly to the exterior to drain. All protection against condensation in the exterior wall assembly must be provided in accordance with the International Energy Conservation Code.
There are exceptions to weather protection: a weather-resistant exterior wall envelope is not required over concrete or masonry walls that are designed in accordance with code, and compliance with the requirements for a means of drainage are not required for an exterior wall envelope that has been tested and proven to resist wind-driven rain. This includes joints, penetrations, and intersections with different materials, in accordance with ASTM E 331, but only under the following conditions:
Exterior wall envelope test assemblies must include at least one opening, one control joint, one wall/eave interface, and one wall sill.
All tested openings and penetrations must be representative of the intended end-use configuration.
Exterior wall envelope assemblies must be tested at a minimum differential pressure of 6.2 pounds per square foot.
Exterior wall envelope assemblies must be subjected to a minimum test exposure duration of two hours.
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Exterior wall design has to be considered to resist wind-driven rain and the results of such testing have to indicate that no water could penetrate any control joints in the wall, joints at the perimeter of openings, or intersections of terminations with different materials. The structural aspects of exterior walls and associated openings must be designed in accordance with Structural Design. |
If a building or structure is in an area considered to be a flood zone, it is required that exterior walls extend below the design floor elevation and are resistant to water damage. Wood must be treated by a pressure-preservative in accordance with AWPA U1 for the species, product, and end use using a preservative that is found in Section 4 of AWPA U1 or decay-resistant heartwood of redwood, black locust, or cedar.
All materials used must be of a code-approved type. When constructing a water-resistive barrier a minimum of one layer of asphalt felt, which must be No. 15, complying with ASTM D 226 for Type 1 felt, or other approved materials must be attached to the studs or sheathing. This must include flashing. This is to provide a continuous water-resistive barrier behind the exterior wall veneer.
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In flood hazard areas that are subject to high-velocity wave action, electrical, mechanical, and plumbing system components cannot be mounted on or penetrate through exterior walls that are designed to break away under flood loads. |
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If you have chosen to construct exterior walls with cold-rolled copper, the copper needs to conform to the requirements of ASTM B 370 and all lead-coated copper must conform to the requirements of ASTM B 101. |
Please refer to the following list for materials and the chapter for which they must be in accordance with:
Concrete and glass-unit masonry: Exterior walls of concrete construction must be designed and constructed in accordance with code requirements.
Plastics: Plastic panel, apron, or spandrel walls as defined by this code are not limited in thickness, provided that plastic and their assemblies conform to code requirements and are constructed of approved water-resistant materials of adequate strength to resist the wind loads for cladding.
Vinyl siding must be certified and labeled as conforming to the requirements of ASTM D 3679 by an approved quality control agency.
Fiber cement siding must conform to the requirements of ASTM C 1186 and be identified on the label listing an approved quality control agency.
Flashing must be installed in such a manner so as to prevent moisture from entering the wall or to redirect it to the outside. The following list contains all of the perimeters in which flashing must be installed:
Perimeters of exterior door and window assemblies
Penetrations and terminations of exterior wall assemblies
Flashing: Pieces of sheet metal, or the like, used to reinforce and weatherproof the joints and angles of a roof, as where a roof comes in contact with a wall. |
Exterior wall intersections with roofs, chimneys, porches, decks, balconies, and similar projections
Built into gutters and similar locations.
Flashing with projection must be installed on both sides and the ends of copings, under sills, and continuously above projecting trim. Moisture is also known to build up in exterior wall pockets and even crevices of buildings and structures. It is crucial that these wall pockets be avoided or protected by using caps or drips.
Flashing and weepholes must be located in the first course of masonry above the finished ground level. This includes the level above the foundation wall or slab. There are other points of support, including structural floors, shelf angles, and lintels where anchored veneers are designed in accordance with this section.
Wood veneers that are found on exterior walls of buildings of Type I, II, III, and IV construction cannot be less than 1 inch thick. Exterior hardboard siding cannot be less than 0.438 inch and must conform the following:
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Flashing and weep holes in anchored veneer shall be located in the first course of masonry above finished ground level above the foundation wall or slab, and other points of support. |
The veneer cannot be more than three stories in height, measured from the grade plane.
Where fire-retardant-treated wood is used, the height cannot be more than four stories.
The veneer is attached to or furred from a noncombustible backing that is fire-resistance rated as required by other provisions of this code.
Where open or spaced wood veneers (without concealed spaces) are used, they cannot project more than 24 inches from the building wall.
When using anchored masonry veneer it is important to remember that not only does it have to comply with this code, but also to ACI 530/ASCE 5 and TMS 402. Anchored masonry veneers in accordance with this chapter are not required to meet the tolerances in Article 3.3 G1 or ACI 530.1/ASCE 6/TMS 602, but slab-type veneer units no more than 2 inches in thickness must be anchored directly to masonry, concrete, or stud construction.
If veneer units are of marble, granite, or other stone units of slab and are from ties of corrosion-resistant dowels in drilled holes, they must be located in the middle third of the edge of the units. The spacing of these units cannot be more than 24 inches maximum. Each unit cannot have less than four ties per veneer unit and cannot be more than 20 square feet in area.
If you choose to use veneer ties made of metal, make sure they are smaller in area than 0.0336 by 1 inch or, if made of wire, not smaller in diameter than 0.1483 inch wire. Some people prefer anchored terra cotta or ceramic units to use on exterior walls of buildings. These too have to be installed according to code restrictions.
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Where the combustible exterior wall covering is furred from the wall and forms a solid surface, the distance between the back of the covering and the wall shall not exceed 1 |
Wood veneer must not exceed 40 feet in height above grade. |
Whether terra cotta is tied or not, the minimum thickness is 1.625 inches and it must be directly anchored to masonry, concrete, or stud construction. Tied terra cotta or ceramic veneer units, along with the minimum thickness of 1.625 inches, must also have projecting dovetail webs on the back surface spaced approximately 8 inches. Veneer ties must have sufficient strength to support the full weight of the veneer in tension. Adhered masonry veneer must comply with the applicable requirements in Section 1405.9.1 and Sections 6.1 and 6.3 of ACI 530/ASCE 5/TMS 402.
Metal supports for exterior metal veneer must be protected. You can paint, galvanize, or use another coating or approved treatment. Wood studs, furring strips, or other wood supports for exterior metal veneer must be approved and pressure treated. Joints and edges that are exposed to the weather must be caulked with a durable waterproofing material to prevent moisture from seeping in. Grounding of metal veneers on buildings must comply with the requirements of this code or the ICC Electrical Code.
When using this next type of veneer—glass—there are a number of guidelines you must follow. The area of a single section of thin exterior structural glass veneer cannot be more than 10 square feet in cases where it is not more than 15 feet above the level of the sidewalk or grade level below, and cannot be more than 6 square feet where it is more than 15 feet above that level.
Neither the length nor the height of the glass can be more than 48 inches, nor can the glass be any thicker than 0.344 inch. Only apply the glass veneer after making sure that the backing is thoroughly dry. You must apply an approved bond coat as well. Make sure this is applied uniformly over the entire surface of the backing so as to effectively seal the surface. The glass can then be set in place with mastic cement so that at least 50 percent of the area of each glass unit is directly bonded to the backing by mastic not less than 0.25 inch thick and not more than 0.625 inch thick. The mastic cement must be of an approved kind, and make note that the bond coat and mastic must be evaluated for compatibility and must bond firmly together.
Where open or spaced wood veneers that don’t have concealed spaces are used they shall not project more than 2 feet from the building wall. |
In areas where glass extends to a sidewalk surface, each section must rest in an approved metal molding and be set at least 0.25 inch above the highest point of the sidewalk. The space between the molding and the sidewalk must be thoroughly caulked and made water tight. If set above sidewalk level and/or above 36 inches, the mastic cement binding must be supplemented with approved nonferrous metal shelf angles located in the horizontal joints in every course. These shelf angles cannot be less than 0.0478-inch thick and no less than 2 inches long and must be spaced at approved intervals; with no less than two angles for each glass unit.
Securing angles to the wall or backing should be done with expansion bolts, toggle bolts, or by other approved methods. If you decide you want to use glass veneers realize that there are specifications for the use of joints. Unless otherwise specifically approved by the building official, abutting areas must be ground square and mitered joints cannot be used except where specifically approved for wide angles.
All glass veneers must be held in place by the use of fastenings at each vertical or horizontal edge, or at the four corners of each glass unit, securing the fastenings to the wall or backing with expansion bolts, toggle bolts, or by other methods. The exposed edges of structural glass veneer must be flashed with overlapping corrosion-resistant metal flashing and caulked with a waterproof compound to prevent moisture from coming between the glass veneer and the backing.
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Glazing between the floor and a height of 24 inches must be fixed or have openings that will not allow a 4-inch diameter sphere to pass through. One exception to this is openings that are provided with no window guards that comply with ASTM F 2006 or F 2090. |
Vinyl siding: A shaped material, made principally from rigid polyvinyl chloride (PVC) that is used as an exterior wall covering. |
Where the opening of the sill portion of an operable window is located more than 72 inches above the finished grade, the lowest part of the clear opening of the window must be a minimum of 24 inches above the finished floor surface of the room in which the window is located. This applies to the following list of occupancies:
Groups R-2
Groups R-3
One family
Two family
Multiple family dwellings.
Vinyl siding conforming to the requirements of this section and complying with ASTM D 3679 must be allowed to be installed on exterior walls of buildings of Type V construction located in areas where the basic wind speed does not exceed 100 miles per hour and the building height is less than or equal to 40 feet in Exposure C.
In areas where construction is located where the basic wind speed is more than 100 miles per hour, or in building heights are over 40 feet, tests or calculations in compliance with the code must be submitted.
Secure all vinyl siding to the building to protect exterior walls of the building from weather. Siding is to be applied over sheathing or other acceptable materials, and applied to conform to water-resistive barrier requirements in this chapter. Even the nails that you use to apply the siding are specified as to size. Unless otherwise specified in the manufacturer’s instruction, nails and accessories must have a minimum of 0.313-inch head diameter and 0.125-inch shank diameter.
All nails must be corrosion resistant and most importantly long enough to penetrate the studs or nailing strip of at least 0.75 inches. If you have chosen fiber cement siding for your building or structure, make sure the panels are installed with the long dimension parallel to framing. Vertical joints must occur over framing members and must be sealed with caulking or covered with battens. Use Z-flashing and solid wood framing for horizontal joints. Lap siding must be lapped a minimum of 1 ¼ inches and the ends must be sealed with caulking covered with an H-section joint cover.
inch.