Glossary

Browse common terms used in commercial and residential roofing. Select a term below or use the search to find specific definitions.

Box GuttersComponent - A box gutter is a rectangular gutter that is built into the roof edge or wall structure and directs water to discharge points like downspouts, typically used on... More

Coping CapComponent - A coping cap is a covering installed on top of a wall at the roof edge that covers and protects where the roof covering ends. More
Core SampleInspection - A core sample (core cut) is a small, cylindrical section of a roof system that is cut and removed to evaluate the roof’s construction, materials, thickness, and condition... More

Internal DrainComponent - An internal drain is a roof drain installed in the roof surface that collects water and directs it into piping inside the building. More

LayoverInstallation – A layover (recover or overlay) is a method of installing a new roof membrane over an existing roof system without removing the existing roof. More
Low-Slope RoofsRoof Types - Low-slope roofs (flat roofs) are a type of roof system with less than a 3:12 pitch, most commonly found on commercial and industrial buildings. More

NDL WarrantyCompliance - An NDL (No Dollar Limit) Warranty is a manufacturer-backed commercial roofing warranty that covers the cost of repairing qualifying leaks without a monetary cap. More

Overflow DrainComponents - An overflow drain (backup drain) is a secondary roof drain installed above the primary drain to prevent water from accumulating on a roof if the primary drains become... More

Parapet WallsComponent - A parapet wall is the portion of an exterior wall that extends above the roofline at the perimeter of some buildings. More
PondingPerformance - Ponding water is accumulated water that remains on a roof surface for more than 48 hours after rainfall. More
Pull TestCompliance - A pull test measures how strongly a roofing fastener grips the roof deck by determining the force required to pull it out. More

Roof DeckComponents - A roof deck is the structural surface connected to a building’s framing that supports the roof system installed above it. More
Roof SystemRoof Types - A roof system (roof assembly) is the entire series of roofing layers and components above the roof deck that work together to weatherproof the building. More

Single-Ply MembraneMaterial - A single-ply membrane is a roof covering that uses one continuous layer of material to waterproof low-slope roofs. More
Split BootComponent – A split boot is a type of flashing with a built-in seam that allows it to wrap around a penetration when a standard one-piece boot cannot be installed... More
Structural SlopePerformance - Structural slope is the intentional pitch built into a roof’s framing or deck to direct water toward drains or roof edges. More

Termination BarComponent - A termination bar (T-bar) is a metal strip used to secure and seal the edge of a roof membrane where it ends against a vertical surface. More
Thermal MovementPerformance - Thermal expansion is the movement of roofing materials as they expand when heated and contract when cooled. More
TPOMaterial - TPO (thermoplastic polyolefin) is a white roof covering used on flat (low slope) roofs, commonly installed on commercial buildings to create a continuous waterproof surface. More

Wind UpliftPerformance - Wind uplift is the upward force exerted on a roof system when wind over a building creates suction and pulls against the roof assembly. More