The Structure of a House Roof

Framing

• The term "roof framing" refers to the structural skeleton that sits atop a building's walls and serves as support for overlaying roof-covering materials. The three most common types of roof framing are rafters, trusses and joists. In general, the term "rafters" refers to sloped beams that run from a roof's peak to a roof's eaves. The term "truss" refers to prefabricated, typically triangular roof support members. Joists are beams that run horizontally from wall to wall to support flat roof structures.

Sheathing

• Roofers fasten sheathing, also called roof decking, directly atop roof framing. Sheathing materials include sheet goods such as plywood or oriented strand board (OSB), or dimensional lumber such as planking. Sheathing provides an extra layer of support and a nailing surface for roof-covering materials.

Roofing Paper

• A layer of roofing paper, also called "tar" paper or felt, sits between the sheathing and many roof-covering materials, such as asphalt shingles. Roofing paper sheds water and inhibits sunlight, providing an initial layer of protection to sheathing.

Roof-Covering Material

• The final part of a house roof is the finished roof covering. Asphalt shingles, sometimes called composition shingles, are a common roofing material. Other recognizable roof-covering materials are corrugated metal panels, wooden shingles and ceramic roof tiles.