Part Two: Roofing Terminology Explained
Nosing: Metal flashing bent at a 90° angle and is installed around roof perimeters, curbs, platforms, etc., in order to protect the roofing system. Nosing should not be used in place of a drip edge.
Penetration: Any object that pierces the surface of the roof.
Rake: A slanting edge of a gabled roof extending beyond the end wall of the house.
Rafter: A rafter is a parallel beam that supports the roof, and is part of the truss. They are the main frame of the roof. Sheathing is nailed to the rafters.
Ridge: The highest point of the roof that runs the length of the roof.
Roof Truss: A truss is a triangular wood structure that supports the roof and gives it added strength. It takes several trusses to build the structure that supports the roof.
Sheathing: Also called decking, it covers the rafters. Tar paper or another type of underlayment is laid on top of it. Plywood is the most common material used for decking. Once the underlayment is installed to the sheathing, the roofing materials are ready to be installed.
Slope or Pitch: The number of inches of vertical rise in a roof, per 12-inches of horizontal distance.
Soffit: The finished underside of the eaves. Covers the area between the end of the eaves and the house.
Square: One hundred square feet of roof.
Steep Slope: Generally all slopes higher than 4/12 are considered steep slopes.
Substrate: The surface that the roof is installed upon.
Tear-Off: Removal of existing roofing materials down to the roof deck.
Truss: Engineered components that supplement rafters in many newer homes and buildings. Trusses are designed for specific applications and cannot be cut or altered.
Underlayment: The material (usually an asphalt-base rolled material) laid on top of sheathing before roofing material is installed
Valley: The less-than 180-degree angle where two adjoining sloped roof planes intersect on a roof creating a “V” shaped depression.
Vapor: Term used to describe moisture-laden air.
Vapor Retarder: A material designed to restrict the passage of water vapor through a roof system or wall.
Vent: An opening or device used to permit air or vapor to exit an enclosed structure.