What Do I Need to Roof a 40 X 80 Metal Building?

Structure

• As with any roofing project, installing a roof on a 40-by-80 foot building requires a structure on which to build. Prior to the roof installation, the foundation, the subfloor and the walls of the building must be constructed. A metal building’s walls consist of steel joists that run vertically and support a top wall plate. This top wall plate, also crafted of steel, sits horizontally across the tops of the joists. Roofing materials attach to this plate.

Trusses

• Instead of creating a joist structure, which likely won’t provide enough support for the roof of a 40-by-80 foot building, trusses should generally be used. Trusses are self-contained cross-sections that have a series of supports throughout them and have the ability to span long distances without breaking, much like the supports that hold up a bridge. In the case of a 40-by-80 foot building, 40-foot trusses should be used and placed between the wall plates in the narrowest direction of the building.

Spacing

• When it comes to supporting a large roof, such as that on a 40-by-80 foot building, you must space trusses at the proper intervals to effectively support the roofing materials. The best spacing for trusses depends upon the build of the truss. Often, the manufacturer recommends the amount of space required between trusses. Generally, though, the spacing of 40-foot trusses on a 40-by-80 foot building is between 4 to 8 feet.

Hardware

• The hardware used to install the trusses on a 40-by-80 foot building depends on the material of the building. Wood trusses are usually nailed to the top plates on the walls while metal trusses must be installed with bolts into metal top plates. Once all of the trusses are secure, you must cover them with roofing panels made of either plywood or flattened metal. At this point, the roof can be covered with tin roofing, shingles or any type of standard roofing material.