Roofing Glossary: I to L

a mass of ice formed at the transition from a warm to a cold roof surface, frequently formed by refreezing melt water at the overhang of a steep roof, causing ice and water to back up under roofing materials.

The slope of a roof expressed in percent or in the number of vertical units of rise per horizontal unit of run.

a material applied to reduce the flow of heat.

any of the small timbers, metal or wood beams arranged parallel to each other and spanning from wall to wall to support a floor, ceiling, or roof of a building.

an asphalt-based roof cement formulated to adhere overlapping plies or asphalt roll roofing.

occurs where overlapping materials are seamed, sealed or otherwise bonded.

a soft malleable, heavy metal; has low melting point and a high coefficient of thermal expansion.

the sprayed polyurethane foam that results from a pass. It usually is associated with a certain pass thickness and has a bottom layer, center mass and top skin in its makeup.