Glossary

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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.