Champaign & Urbana
(217) 355-7663
Bloomington & Normal
(309) 361-7663
The Roofing Dog 2013 Small Business of the Year!!!

Roofing Terms and Glossary

Home » Roofing 101 » Roofing Terms and Glossary
Below are common terms and phrases associated with residential roofing.
Asphalt Shingle – A shingle manufactured by coating a reinforcing material (felt or fibrous glass mat) with asphalt and having mineral granules on the side exposed to the weather.
Caulking – The physical process of sealing a joint or juncture, or sealing and making weather-tight the joints, seams or voids between adjacent surfaces by filling with a sealant.
Closed Valley – A valley where the flashing is covered by shingles.
Deck/sheathing: The surface, usually plywood or oriented strand board (OSB) to which roofing materials are applied.
Dormer: A small structure projecting from a sloped roof, usually with a window.
Drip Edge: An L-Shaped strip (usually metal) installed along roof edges to allow water run off to drip clear of the deck, eaves and siding.
Eave: The horizontal lower edge of a sloped roof.
Fascia: A flat-board, band or face located at a cornice’s outer edge.
Felt/underlayment: A sheet of asphalt –saturated material (often called tar paper) used as a secondary layer of protection for the roof deck.
Fire Rating: System for classifying the fire resistances of various materials. Roofing materials are rated Class A, B or C, with Class A materials having the highest resistance to fire originating outside the structure.
Flashing: Pieces of metal used to prevent the seepage of water around any intersection or projection in a roof system, such as vent pipes, chimneys, valleys and joints at vertical walls.
Hip Roof – A roof, which rises by inclined planes from all four sides of a building. The line where two adjacent sloping sides of a roof meet is called the hip.
Louvers: Slatted devices installed in a gable or soffit (the underside of eaves) to ventilate the space below a roof deck and equalize air temperature and moisture.
Open Valley – A valley where the flashing is exposed to the weather.
Oriented Strand Board (OSB): Roof deck panels (4 by 8 feet) made of narrow bits of wood, installed lengthwise and crosswise in layers and held together with a resin glue. OSB often is used as a substitute for plywood sheets.
Penetrations: Vents, pipes, stacks chimneys – anything that penetrates a roof deck.
Rafters: The supporting framing to which a roof deck is attached.
Rake: The inclined edge of a roof over a wall.
Ridge: The top edge of two intersecting sloping roof surfaces.
Ridge Cap – Formed shingles, shake or tile used to cover the ridge of a building. Make sure that specially designed cap products are used. Many roofers will use materials not made for this purpose.
Ridge Vent: A ventilation system placed over a cut slot in the ridge line to allow air flow out of the attic space
Sheathing: The boards or sheet materials that are fastened to rafters to cover a house or a building.
Slope: Measured by rise in inches for each 12 inches of horizontal run: A roof with a 4-in-12 slope rises 4 inches for every foot of horizontal distance.
Soffit – A board or sheet that extends from the fascia to the buildings siding and hides the bottom of an overhang. Soffit may or may not contain ventilation slots depending on the attic venting system used.
Starter Course – The first course of shingles installed on a roof, starting at the lower left edge of the eave.
Step Flashing – Metal shingles or plates used in a stair-step pattern under regular shingles. Step flashing is the recommended flashing whenever a wall or chimney is above the roof line.
Square: The common measurement for roof area. One square is 100 square feet (10 by 10 feet).
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– A sheet material that is used to separate the roof deck and the roof system.
Valley: The angle formed at the intersection of two sloping roof surfaces.
Vapor Retarder: A material designed to restrict the passage of water vapor through a roof system or wall.
Vent – An outlet for air; vent pipe in a plumbing system; a ventilating duct