Roofing Terms & Definitions

Asphalt:  A bituminous waterproofing agent applied to roofing materials during manufacturing.

Back Surfacing:  Fine mineral matter applied to the backside of shingles to keep them from

Blisters:  Bubbles that may appear on the surface of asphalt roofing after installation.

Built-up roof:  A flat or low-sloped roof consisting of multiple layers of asphalt and ply sheets.

Caulk:  To fill a joint with mastic or asphalt cement to prevent leaks.

Class "A":  The highest fire-resistance rating for roofing as per ASTM E-108.  Indicates roofing
is able to withstand severe exposure to fire originating from sources outside the building.

Class "B":  Fire-resistance rating that indicates roofing materials are able to withstand moderate
exposure to fire originating from sources outside the building.

Class "C":  Fire-resistance rating that indicates roofing materials are able to withstand light
exposure to fire originating from sources outside the building.

Concealed nail method:  Application of rolled roofing in which all nails are driven into the
underlying course of roofing and covered by a cemented, overlapping course.  Nails are not
exposed to the weather.

Condensation:  The change of water from vapor to liquid when warm, moisture-laden air comes
in contact with a cold surface.

Coverage:  Amount of weather protection provided by the roofing material.

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.

Downspout:  A pipe for draining water from roof gutters.  Also called a leader.

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.

Edging Strips:  Boards nailed along eaves and rakes after cutting back existing wood shingles to provide secure edges for re-roofing with asphalt shingles.

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.

Flashing:  Pieces of metal or roll roofing used to prevent seepage of water into a building around any intersection or projection in a roof such as vent pipes, chimneys, adjoining walls, dormers and valleys.

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.

Gable:  The upper portion of a sidewall that comes to a triangular point at the ridge of a sloping roof.

Granules:  Ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.

Gutter:  The trough that channels water from the eaves to the downspouts.

Insulation:A rigid board of various widths from 1/2 "to 6", usually applied with some form of mechanical fasteners. When more than one layer is applied the second layer will be applied with an adhesive, either hot or cold.

Interlocking shingles:  Individual shingles that mechanically fasten to each other to provide wind resistance.

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.

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.

Overhang:  That portion of the roof structure that extends beyond the exterior walls of a building.

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

Pitch:  The degree of roof incline expressed as the ratio of the rise, in feet, to the span, in feet.

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.

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

Soffit:  The finished underside of the eaves.

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).

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 layer of asphalt saturated  (sometimes referred to as tar paper) which is laid down on a bare deck before shingles are installed to provide additional protection for the deck.

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:.  Any device installed on the roof, gable or soffitt for the purpose of ventilating the underside of the roof deck.