Commercial Roofing Glossary

Commercial Roofing Glossary

Absorption:

The ability of a material to accept and retain a liquid, often related to the capacity of insulation or roofing to retain water.

Adhesion:

The bonding power of a material. In roofing, dry surfaces can bond by applying pressure.

Aggregate:

Crushed stone, gravel, or other granular materials that protect and weigh down a roof surface or provide a finished surface.

Apron Flashing:

A term used for a flashing located at the juncture of the top of the sloped roof and a vertical wall or steeper-sloped roof.

Asphalt:

A sticky, black, and highly viscous liquid or semi-solid form of petroleum, often used in waterproofing products and roofing shingles.

Ballast:

A material, often stones, used to weigh down and stabilize roofing components.

Bitumen:

A black viscous mixture of hydrocarbons used in roofing and asphalt.

Blister:

A raised area on the roof, often filled with air or water, indicating separation beneath the surface.

Built-Up Roof (BUR):

A type of roofing made up of alternating layers of tar and reinforcing fabric.

Cant Strip:

A beveled or triangular-shaped piece of wood, metal, or foam used to ease the transition from a horizontal roof deck to a vertical surface.

Cap Sheet:

The top layer in specific roofing systems, typically granulated and UV resistant.

Coating:

A liquid-applied substance used to protect and seal roofing materials.

Crickets:

A peaked construction used to divert water around obstructions on the roof.

Deck:

The structural substrate, usually made of wood or metal, over which roofing materials are applied.

Dormer:

A small structure with a window that projects from a sloped roof.

Downspout:

A pipe that carries rainwater from a roof to a drain or ground level.

Drip Edge:

An edging device installed along the outermost perimeter of the roof to direct water runoff.

Eave:

The overhanging lower edge of a roof.

EPDM:

Ethylene propylene diene monomer, a type of synthetic rubber roofing membrane.

Expansion Joint:

A device used to allow for the expansion and contraction of different construction materials.

Fascia:

The vertical board around the edge of a roof.

Fasteners:

General term for nails, staples, screws, or bolts used to secure roofing material.

Flashing:

Materials used to prevent water infiltration when the roof intersects with another surface.

Gable:

The triangular section of the outer wall at the edge of a pitched roof.

Galvanized Steel:

Steel coated with a layer of zinc for corrosion resistance.

Granules:

Small, gravel-like particles that coat the top of shingles, providing UV protection and color.

Gutter:

A channel that collects and diverts rainwater shed by the roof.

Hip:

The external angle formed by the intersection of two sloping roof planes.

Insulation:

Materials that reduce heat transfer into or out of a building.

Joist:

Horizontal beams that support the roofing system.

Lap:

The part of the roofing material that overlaps a section of adjacent material.

Mansard:

A type of roof with four sloping sides, each of which becomes steeper halfway down.

Membrane:

A flexible or rigid material, either pre-formed or formed in place, used to waterproof roofs.

Modified Bitumen:

A roofing material made from asphalt reinforced with fiberglass or polyester.

Nailer:

A wood or metal securement on top of or to the side of the roof deck that provides a receiving medium for the fasteners.

Parapet:

A wall-like structure at the edge of a roof.

Penetration:

Any object, such as a pipe or stack, which passes through the roof.

Pitch:

The angle or slope of a roof.

Ply:

A layer of roofing material; multiple layers form a built-up roof system.

PVC:

Polyvinyl Chloride, a type of single-ply roofing system.

Rafter:

The framing beams supporting the roof deck, running from the ridge to the eaves.

Ridge:

The top edge where two sloping sides of a roof meet.

Scupper:

An opening in a wall or parapet for the drainage of water from a roof.

Seam:

The joint or connection between two adjacent sections of roofing material.

Single-Ply Roofing:

A roofing system with a single material layer as the primary and topmost watertight surface.

Soffit:

The exposed surface beneath the overhanging portion of a roof eave.

TPO:

Thermoplastic Olefin, a type of single-ply roofing material.

Underlayment:

A layer of material placed between the roof deck and the roofing material, often for waterproofing.

Valley:

The angle formed at the intersection of two sloping roof surfaces.

Vapor Retarder:

A material designed to resist the migration of water vapor.

Vent:

An opening or device that permits air or vapor to exit the roofing system.

Waterproofing:

The process or treatment of making a structure resistant to water infiltration.

Weathering:

The natural deterioration of materials due to environmental factors.

Weep Hole:

A small opening that allows for drainage of water.

Wind Uplift:

The force exerted by wind below roofing components, potentially lifting them off the structure.