It is a common notion that a shipping container house doesn’t need a separate roof, as it already has a top enclosure. However, this is far from true – the roof of the container can be used as it is only for shipping cargo and not for container homes. This is especially true for homes that use multiple containers – stacked vertically or horizontally. The top of a shipping container is designed with corrugation and an upward incline to displace accumulated water. When two containers are joined together, it closes the gap formed by the corner offset, thereby forming a pool of stagnated water.
The different types of roofs that can be built for a shipping container home are:
1. Shed:
A shed is a sloping roof that is easy and cheap to construct. The advantage of a shed type is that you can fit solar panels on the rooftop to meet your electricity needs. You must know basic welding techniques for a DIY roof welding.
a. Two steel plates at right angle (900) to each other are welded across the length of the container on both sides.
b. Two wooden beams are fixed into the steel plates; the truss will be fixed into the beams
c. Once the beams are fixed, screw the roof truss into place
d. Place beams across the roof to complete the entire roofing structure
Note: It is important that your roof has sufficient ventilation – provide a roof overhang over the container for ventilation. There must also be an inch gap in the soffit board and be covered with a mesh to allow air circulation into the roof.
2. Gable Roof:
A Gable roof is similar to a shed roof but with an incline on both sides. Following are the steps to follow to install a gable roof:
a. Calculate the rafter length using Pythagoras theorem or Chalk Line Duplication method; you can also buy reference guides that calculate the rafter lengths for a given pitch
b. Two steel plates at right angle (900) to each other are welded across the length of the container on both sides.
c. Install ceiling joists on the steel plates – you can use 2x4 lumber
d. Use 2x6 lumber to cut a ridge board – this goes on the roof peak
e. For safety purposes, lay planks on the ceiling joists – you can stand on them and remove the planks after framing the roof completely
f. Cut the rafters (based on your calculations) and place them at 16” or 24” intervals
g. Attach collar ties at peak of the roof to strengthen the rafters
h. Assemble the gable roof and fix the planks to rafters – the planks must be parallel to the ridge board
i. Cover the end of the gable roof with mitered planks
Irrespective of the type of roof you install, it is advisable to consult a structural engineer to design the beams and rafters. A structural engineer will also be able to advise you on the ventilation options for various roofing systems. If you decide not to replace the container roof, apply a layer of tarpaulin sheet and cover it with asphalt – this will act as a barrier between your roof and condensation issues.
If you are attaching multiple containers, or want to add windows, doors and/or aesthetic value to your container home, it will be necessary to cut open one or more container walls. You can use a plasma cutter, grinder, cutting torch, or even a jigsaw to cut the container; using a plasma cutter gives you smooth edges with a much cleaner cut than the other options. It is advisable to get professional help, as it reduces the risks and dangers involved in cutting structural steel. Following are some precautions to be taken before you proceed with cutting the container:
1. Wear heavy duty leather gloves and eye protection
2. Cutting steel will produce high decibel noise – protect your ears with ear plugs
3. The metal shavings from the cutting will be extremely hot – wear heavy duty full sleeved shirt and long pants to protect yourself
4. Before you start cutting, make arrangements to secure the pieces that will be dislodged during the cutting process
5. The cut panels will be heavy for a single person to move (if you are cutting out an entire wall)
Cutting open the sidewalls will leave large gaps in your container. You can fill these gaps using caulk, spray foam, or coarse steel wool.