Glossary of Roofing Terminology


The wood product-usually rough lumber or plywood -to which the roofing shingles are installed. These boards are fastened to the rafters of the roof.

A small structure projecting from a sloped roof, usually with one or more windows.  There are many types of dormers including gable dormers and shed dormers.

Drip edge:
A flashing (usually metal) applied around the roof edges to help water coming off the roof drain properly.  Drip edge tries to direct water to “drip” to the ground or surface below rather than run down the fascia or siding.

The horizontal lower edge of sloped roof usually attached to the rafter tails (ends of roof rafters).

A flat board, band or face located at the outer edge of the roof.  This term is sometimes uses interchangeably with “Eave”.

A sheet of asphalt-saturated material–either paper or fiberglass (often called “tar paper”) used as a layer of protection between the shingles and sheathing.

Pieces of metal used to prevent the seepage of water around any intersection or projection in a roof, such as vent pipes, chimneys, valleys, and the joints at vertical walls.

Fire rating:
The Underwriters Laboratories (UL) system for classifying the fire-resistance of various materials. Roofing materials are “Class A,” “B” or “C,” with “A” materials having the highest resistance to fire originating outside the structure.

Slatted devices installed in the gable or soffit (the underside of the eaves) to ventilate the space below the roof deck and equalize air temperature and moisture.

Oriented-strand board/OSB:
Roof deck panels (4’ x 8’) made of narrow bits of wood, laid down lengthwise and crosswise in layers, held together with a resin “glue.” Often used as a substitute for plywood sheets.

Vents, pipes, stacks, chimneys-anything that sticks up through the roof deck.

The supporting framing to which the roof deck is attached.

The inclined edge of a roof over a wall.

The top edge of two intersecting sloping roof surfaces.

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.

The common measurement for roof area-100 square feet (10’ x 10’)

The engineered components which have supplemented rafters in many newer houses. They are designed for specific applications and cannot be cut or altered in any way.

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 or wall.
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