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by Katie Lee

22 roofing terms to know: test your knowledge!

By Steve Manser

Properly maintaining and managing your restaurant or retail facility’s roof can be tough. Having a basic knowledge of a roof’s components will help you communicate easier with your roofing provider and be more knowledgeable when it comes to inspections and invoices.

Even the most experienced facility managers who may claim to have “seen it all” need to stay current on roof maintenance best practices, newer materials and technology being used in commercial roofing, and changes to building codes that impact the roof.

Sure, a trusted roofer should be armed with this information, as well, but the more you can talk the talk, know what questions to ask and remain observant as to what to look for when your roof is being worked on, the more effective you’ll be managing this critical — and sometimes expensive to maintain — asset.

Following is a list of commonly used terms in roofing today, and how they might be applied to your needs in managing your building’s roof.

Aggregate: Granular material such as gravel or slag used as a surfacing layer in a built-up roof.

Blisters: A common roof defect consisting of an enclosed pocket of air — and perhaps water — trapped between layers of felt or membrane, or between the membrane and substrate.

Built-Up Roof (BUR) Membranes: A roof system comprised of layers of bitumen (asphalt or coal tar) and reinforcing plies (felts or fabrics) and surfacing (options include aggregate, ceramic granules, liquid coatings).

Coating: A layer of liquid-applied chemical material to a roof’s surface for the purpose of waterproofing, thermal protection and/or aesthetics.

Coping: The top layer or course of a masonry wall, usually having a slanting upper surface to shed water.

Counterflashing: Formed metal or elastomeric sheeting that covers and protects the top edge of membrane base flashings.

Decking: A structural component of roof assembly — typically the base layer — and made of metal, concrete, gypsum or wood.

EPDM: A thermosetting synthetic elastomer used in single-ply membranes consisting of terpolymer of ethylene, propylene and diene.

Fasteners: Mechanical securement devices and assemblies such as nails, staples, screws, cleats, clips and bolts used to secure various components of a roof assembly.

Flashing: Membrane-base or sheet metal coverings of the most vulnerable parts of the roof to exterior water entry; commonly where the roof covering is interrupted or terminated.

Gutters: A narrow channel installed along the downslope perimeter of a roof system to collect and divert runoff rain water to the downspouts.

Membrane: A component of roof assembly made of flexible or semi-flexible material installed above the insulation and immediately beneath the surfacing as a waterproofing measure.

PVC: A single-ply roofing system comprised of a membrane made from the synthetic polymer polyvinyl chloride.

R-Value: A measure of a material’s thermal resistance, defined as the mean temperature difference between two defined surfaces of material or construction that induces unit heat flow through a unit area.

Scrim: A component of a roof membrane comprised of woven, non-woven or knitted fabric that’s used for reinforcing or strengthening purposes.

Scuppers: A soldered sheet metal sleeve used to provide an outlet through parapet walls or gravel stops on flat and built-up roofs to allow drainage of excess water.

Seam: A joint formed by the adhering of two separate sections of material.

Single-Ply: A roof system comprised of a single thermoplastic membrane made from a flexible sheet of plasticizers and reinforcements that are seamed by hot air welding or solvent welding.  This is one of the more common roof systems in retail and restaurant markets.

Steep Sloped: Roofs with a pitch greater than 3:12, or 14 degrees.

Substrate: The surface, typically the deck or insulation, upon which the roofing or waterproofing membrane is applied.

Tensile Strength: The strength of a material under tension, which determines a material’s capacity to withstand loads tending to elongate.

TPO: A single-ply roofing system comprised of a thermoplastic olefin membrane.


— Steve Manser is president of Simon Roofing, a national commercial roofing installer/manufacturer that’s among the largest roofing contractors in the United States.

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