Roofing Glossary

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Quick Language Lesson

Pitch and slope are terms used to describe the angles of your roof.

Pitch is the relationship between the roof’s rise — the vertical change in height for each horizontal unit of the roof — and span, which is the distance across your roof.

Slope is the relationship between the roof’s rise and run, or the horizontal change in distance across your roof.

Some Common Roofing Terms...

Cricket : A peaked, V-shaped structure incorporated into the chimney flashing system. Installed on the high side of a chimney, or in a valley in certain roof transitions to divert water and prevent pooling.

Deck/sheathing : The surface, usually plywood, oriented strand board (OSB), or plank board 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 material 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.

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.

Penetrations : Vents, pipes, stacks, chimneys-anything that penetrates a roof deck.

Polyisocyanurate (ISO Board): A form of rigid insulation commonly installed over-top of the roof deck and underneath the flat roofing membrane acting as a smooth, clean substrate for the TPO roof system and providing R-Value for energy efficiencies.

Pipe Collar:: A form of roof flashing installed around a pipe penetration. These flashing fit snuggly around the pipe and extend under the surrounding roof shingles. Common types of collars include neoprene, lead, copper and silicone.

Rake : The inclined edge of a roof over a wall.

Ridge: The top edge of two intersecting sloping roof surfaces.

Rafters : The supporting framing to which a roof deck is attached.

Ridge Vent: A type of vent installed at the peak of a sloped roof which allows warm, humid air to escape a building's attic. Ridge vents are most common on shingled residential buildings.

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.

Square: The common measurement for roof area. One square is 100 square feet (10 by 10 feet).

TPO (Thermoplastic Polyolefin) : a single-ply membrane used for flat/low sloped roofing composed of synthetic components along with a fabric reinforcing scrim that stabilizes and strengthens the membrane for improved and increased performance.

Truss: Engineered components that supplement rafters in many newer homes and buildings. Trusses are designed for specific applications and cannot be cut or altered.

Valley: The angle formed at the intersection of two sloping roof surfaces.