Roofing
Roofing is the construction and covering of the uppermost part of a building. Its primary job is to protect the structure below from rain, snow, wind, sun, and temperature extremes, while also contributing to insulation and appearance.
Basic structure[edit]
A typical roof is made up of several layers:
- Roof deck — the structural base, usually plywood or oriented strand board (OSB)
- Underlayment — a water-resistant barrier between the deck and the outer covering
- Roof covering — the outermost material, such as asphalt shingles or metal
- Flashing — metal pieces that seal joints, valleys, and penetrations such as chimneys and vents
Slope[edit]
Roofs are generally classified by slope. Steep-slope (pitched) roofs shed water quickly and are common on homes, while flat or low-slope roofs are more common on commercial buildings and use membrane systems.