Glossary of Roofing Terms

Deck
The deck is the material installed over the framing of a structure on which the shingles are installed.  The primary materials are Oriented Strand Board (OSB) and plywood.

Double Coverage
Double coverage is a method of applying roof shingles so that two complete layers of material are provided.

Dormer
A dormer is a window unit projecting through the sloping plane of a roof.

Drip Edge
A drip edge is the metal strip used on eves and rakes to allow for water run off without damaging the underlying materials.

Drip Course
A drip course is the first course of shingles that slightly overhangs the edge.

Eave
The eave is the horizontal edge of a roof that projects over the outside wall.

Exposure
Exposure is the portion of the shingle that is exposed to the weather. It is usually measured from the butt of one shingle to the butt of the next overlapping shingle.

Lap
Lap refer to the overlap of one roofing material to another.

Laminated Shingles
Laminated shingles are shingles containing more than one layer of tabs creating extra thickness.

Mastic
Mastic is a type of asphalt roof cement.

Modified Bitumen
Modified Bitumen is a roller roofing membrane with a polymer modified asphalt. The rolls generally have a fiberglass or polyester mat for reinforcement.

Saturant
Saturant is asphalt used to impregnate felt for waterproofing and strength.

Seal Down
Seal down is a factory applied asphalt strip used to bond shingles to the ones above. It is used to provide wind resistance.

Sheathing
Sheathing consists of exterior grade boards that are used as a roof decking.

Skirt Flashing
Skirt flashing is a large often single piece of flashing usually found at the bottom of a dormer.

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