Roofing Terms

Ever wondered what some of those roofing terms and words mean? Here’s your guide to the jargon, lingo, and language used in roofing.

Have questions about any particular part of your roof?

Give the KY-KO team a call! We offer free roofing checkups here in the Phoenix metro, and we’d love to help you answer any questions you have.

Common Roofing Terms


The surface, usually plywood or oriented strand board (OSB), to which roofing materials are applied.


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 runoff to drip clear off the deck, eaves and siding.


The horizontal lower edge of a sloped roof.


The material covering the rafter tails at the end of the roof.

Pictured: Roofing underlayment is one of the main roofing terms that homeowners should know.

Pictured: Exposed roofing underlayment during the installation of a new shingle roof.


A sheet of asphalt-saturated material (often called tarpaper) 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.


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.


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.

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 resin glue. OSB  is often used as a substitute for plywood sheets.


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


The supporting framing to which a roof deck is attached.


The inclined edge of a roof over a wall.


The top edge of two intersecting sloping roof surfaces.


The boards or sheet materials that are fastened to rafters to cover a house or building.


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.


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


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


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.