Seattle Roofing Contractor
Solar Tubes, Gutters and Skylights. Installations and Repairs
(425) 774-0806

Key Roofing Terms

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Aggregate: A surfacing material or ballast for a roof system. Aggregate can be rock, stone, crushed stone or slag, water-worn gravel, crushed lava rock or marble chips

Algae discoloration: A type of roof discoloration (gray or black) caused by algae, also called fungus growth.

Alligatoring: Alligatoring is term used to describe the cracking of surfacing bitumen on a built-up roof. These cracks are the result of the limited tolerance of asphalt to thermal expansion or contraction, and produce a pattern that resembles an alligator’s hide.

Aluminum Roof Coating: Reflection coating installed over built-up roofs and smooth surface torch down.

Attic: The open area above the ceiling and under the roof deck of a pitched roof.

Base flashing: That portion of the flashing attached to or resting on the deck to direct the flow of water onto the roof covering.

Battens: 1″x2″x4′ wood strips nailed to the roof, upon which the field tile hangs.

Bird stop: In addition to preventing birds from nesting in the hollows of the tile, this length of formed metal or foam elevates the first course of tile so that it is positioned at the same angle as subsequent courses.

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

Box scuppers:  Scuppers used on the outside edge of a roof with no overhang

Built-in Gutters: a gutter on the roof deck with a higher fascia board creating a trough to collect water.

Built-up roof: An outer covering of a comparatively flat roof, consisting of 3 layers of saturated felt and 3 layers of tar. As laid, each layer is mopped with hot tar or asphalt. The top layer is finished with a mineral or rock covering and a special coating.

Bundle: A package of shingles. There are 3, 4 or 5 bundles per square.

Butt edge: The lower edge of the shingle tabs.


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