Roof Structures
2011-09-29
A roof structure supports gravity loads such as roofing, rooftop structures, hung interior fixtures, ceilings, and the roof structure itself. It also supports the weight of attic insulation, and often such things as plumbing, AC equipment, and items stored in the attic. A roof structure also protects the interior from the elements, and resists uplift loads during high winds. The roof structure or ceiling may also serve as a structural diaphragm. Many single family home roof structures are constructed with prefabricated wood trusses or hand framed with wood members. Bracing is commonly found in trussed roof structures, particularly near wood frame gable ends. Roof trusses require connections to their supporting element. These may be straps or other anchors which keep the truss in place under wind loads. Ceilings may also be considered to be part of the roof structure, if acting in a bracing or diaphragm capacity. The roof decking, or sheathing, of most modern homes consists of plywood or orientated strand board (OSB). 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 their causes are discussed in Common Problems and Diagnosis.