Roof Structures

A roof structure is a key part in completing the building envelope. It supports gravity loads such as roofing, rooftop structures, hung interior fixtures, and interior ceilings finishes. It also supports the weight of attic insulation, and often plumbing, HVAC, and electrical systems. A roof structure allows the roofing system (shingles, metal, etc.) to protect interior from the elements. The roof structure and ceiling may also serve as a structural diaphragm. This distributes lateral loads, such as wind, to the lower shear walls.

Most single family home roof structures are constructed with prefabricated wood trusses, engineered wood or sawn lumber rafters. The roof decking, or sheathing, of most modern homes consists of plywood or oriented strand board (OSB) sheathing. Older homes may have a roof deck consisting of sawn lumber planks. Commercial and manufacturing buildings often utilize steel, concrete, or both for their roof structures.

All roof structures should be properly braced, attached, and sloped. As with any structural component or system, problems may arise from improper construction, damage, or deterioration of a roof structure. Some common problems with roof structures and potential causes are discussed in the Common Problems tab at left.