Roofing Terms

The following are some of the most used terms in the commercial roofing industry. Contact Seamless Roofing for assistance on your Indianapolis commercial roof.



Alligatoring: The cracking of the surfacing bitumen on a built-up roof, producing a pattern of cracks similar to an alligator’s hide; the cracks may or may not extend through the surfacing bitumen.

Asphalt: A bituminous waterproofing agent used in various types of roofing materials.

ASTM: The American Society for Testing and Materials. Organization that sets standards for a wide variety of materials, including roofing.


Ballast: An anchoring material, such as aggregate, or precast concrete pavers, which employ the force of gravity to hold (or assist in holding) single-ply roof membranes in place.

BOMA: Building Owners & Managers Association. Network of professionals involved in building ownership, management, development and leasing.

Built-Up Roof Membrane (BUR): A continuous, semi-flexible multi-ply roof membrane, consisting of plies or layers of saturated felts, coated felts, fabrics, or mats between which alternate layers of bitumen are applied. Generally, built-up roof membranes are surfaced with mineral aggregate and bitumen, a liquid-applied coating, or a granule-surfaced cap sheet.


Caulking: Sealing and making weather-tight the joints, seams, or voids between adjacent units by filling with a sealant.

Closure Strip: A metal or resilient strip, such as neoprene foam, used to close openings created by joining metal panels or sheets and flashings.

Coping: The covering piece on top of a wall which is exposed to the weather, usually made of metal, masonry, or stone. It is preferably sloped to shed water back onto the roof.

Crickets: A peaked water diverter installed behind chimneys and other large roof projections. Effectively diverts water around projections.


Downspout: A conduit used to carry runoff water from a scupper, conductor head, or gutter of a building to a lower roof level, or to the ground or storm water runoff system.

Drain: An outlet or other device used to collect and direct the flow of runoff water from a roof area.

Drip Edge: A metal flashing, or other overhanging component, with an outward projecting lower edge, intended to control the direction of dripping water and help protect underlying building components. A drip edge also can be used to break the continuity of contact between the roof perimeter and wall components to help prevent capillary action.


Elastomeric Coating: A coating system which, when fully cured, is capable of being stretched at least twice its original length (100% elongation) and recovering to its original dimensions. Used to restore existing roof substrates.

Energy Seal: A supplier/manufacturer of elastomeric roof coatings.

Energy-Star: A government-backed labeling program that helps people and organizations save money and reduce greenhouse gas emissions by identifying factories, office equipment, home appliances and electronics that have superior energy efficiency.

EPDM: Ethylene Propylene Diene Monomer – rubber roof membrane rolled out in sheets.


Fabric: A woven cloth or material of organic or inorganic filaments, threads, or yarns used for reinforcement in certain membranes and flashings.

Fasteners: Any of a wide variety of mechanical securement devices and assemblies, including nails, screws, cleats, clips, and bolts, which may be used to secure various components of a roof assembly.

Fluid Applied: An elastomeric material, fluid at ambient temperature, that dries or cures after application to form a continuous membrane.


Gutter: A channeled component installed along the downslope perimeter of a roof to convey runoff water from the roof to the drain leaders or downspouts.


HVAC: Heating, ventilating, and air conditioning equipment often on top of the roof.


Lap Seam: Occurs where overlapping materials are seamed, sealed, or otherwise bonded.

LEED: (Leadership in Energy and Environmental Design) is an ecology-oriented building certification program run under the auspices of the U.S. Green Building Council (USGBC).


Membrane: A flexible or semi-flexible material, which functions as the waterproofing component in a roofing or waterproofing assembly, and whose primary function is the exclusion of water.

Mil: A unit of measure, one mil is equal to 0.001 inches or 25.400 microns, often used to indicate the thickness of a roofing membrane.

Modified bitumen: Rolled roofing membrane with polymer modified asphalt and either polyester or fiberglass reinforcement.

Monolithic: A roof formed or composed of material without joints or seams – Seamless


NRCA: The National Roofing Contractors Association. Respected national organization of roofing contractors.


Parapet Wall: That part of a perimeter wall immediately adjacent to the roof which extends above the roof.

Penetration: Any object passing through the roof.

Polyvinyl Chloride (PVC): A synthetic thermoplastic polymer prepared from vinylchloride.

Ponding: The excessive accumulation of water at low-lying areas on a roof.

Primer: A thin, liquid-applied solvent-based coating that may be applied to a surface to improve the adhesion of subsequent applications of coatings.


Re-covering: The process of covering an existing roofing system with a new roofing system.

Replacement: The practice of removing an existing roof system and replacing it with a new roofing system.

Ridge Cap: A material or covering applied over the ridge of a roof.

Roof Restoration: The process of restoring an existing roof by applying an elastomeric coating on top of the current roof substrate, without removing the existing membrane.

RoofXtender: An elastomeric roof coating.


Snow Guard: A series of devices attached to the roof in a pattern that attempts to hold snow in place, thus preventing sudden snow or ice slides from the roof.

Standing Seam: A metal roof system that consists of an overlapping or interlocking seam that occurs at an upturned rib. The standing seam may be made by turning up the edges of two adjacent metal panels and overlapping them, then folding or interlocking them in a variety of ways.

Substrate: The surface upon which the roofing or waterproofing membrane is applied (e.g., in roofing, the structural deck or insulation).


Thermal Shock: The stress-producing phenomenon resulting from sudden temperature changes in a roof membrane when, for example, a cold rain shower follows brilliant hot sunshine, which may result in sudden cooling or rapid contraction of the membrane.


Ultraviolet (UV): Situated beyond the visible spectrum, just beyond the violet end, having wavelengths shorter than wavelengths of visible light and longer than those of X-rays.


Waterproofing: Treatment of a surface or structure to prevent the passage of water under hydrostatic pressure.

Wind Uplift: The force caused by the deflection of wind at roof edges, roof peaks or obstructions, causing a drop in air pressure immediately above the roof surface. This force is then transmitted to the roof surface. Uplift may also occur because of the introduction of air pressure underneath the membrane and roof edges, where it can cause the membrane to balloon and pull away from the deck.