7 Important Commercial Roofing Terms To Know

Congratulations on being the proud new owner of a commercial property! With your new building, you get all four walls, a complete floor, and a lovely roof. Question: do you know how to care for your commercial roof? Do you know the various parts of your commercial roof? Let’s get familiar with seven important commercial roofing terms. 

Flashing

Suppose you had two unlike materials — say, brick and wood — and needed to cover the joint between them. What would you use? The material you select would have to last a long time, remain in place, and stand up to every kind of weather. You’d use metal, right? 

This is what flashing is: a thin sheet metal used to bridge the gaps and seams between unlike materials. The International Building Code requires flashing to be not less than 0.019 inches (0.483 mm); the National Roofing Contractors Association (NRCA) recommends no less than 26-gauge in copper or galvanized steel and 0.032 inches in aluminum.

Your commercial roofing contractor will be happy to inspect your building’s flashing to ensure it is up to code, well-adhered, and free of corrosion or rust.  

HVAC

Heating, Ventilating, and Air Conditioning (HVAC) is both a system and an industry. Your HVAC service company needs rooftop access to the large coolers which make your building habitable. The system itself is your HVAC system, and it regulates air temperature and relative humidity inside your property. 

HVAC units usually sit on your low-slope or flat roof on HVAC curbs, raised metal frames surrounding the necessary hole in your roof through which the HVAC system pumps cool air into your building. The seam around the HVAC curb and your roof must be sealed carefully so no water infiltrates your roof deck. 

HVAC workers also must be able to walk your roof to reach the HVAC units. Their boots and equipment are often responsible for unintentional damage to your roof, so most facilities managers monitor rooftop access and enforce a “walkways only” policy. Your commercial roofer can help you with a roof maintenance plan

R-Value

Insulation works by resisting the flow of thermal energy — heat — from one area or region to another. This resistance is measured in R-value, with higher numbers indicating greater ability to resist heat flow. The better a rooftop insulation, the higher its R-value. 

The 2018 IECC Commercial Scope and Envelope Requirements from the U.S. Department of Energy cite a minimum of R-25 roof deck insulation in mild climates (Florida and the Southwest), increasing to a minimum of R-35 in colder areas. Is your roof energy compliant? 

Substrate

Substrate refers to the layers beneath the visible layer of your commercial roof. Your roof deck may be skinned in corrugated sheet metal; this is the substrate onto which rigid foam insulation and, perhaps, a single-ply membrane is attached. Substrates can include other types:

  • Open deck framing (wood or steel)
  • Plywood
  • Oriented strand board (OSB)
  • Concrete

An existing roof could be considered a substrate if you plan to have another roofing system laid on top of it. 

As a general rule, commercial roofers will want to ensure the substrate is in excellent shape before installing a new roof. 

Seam

Almost every commercial roofing material comes in pieces or rolls. Though the rolls may be extremely wide (some are 20 feet wide!), one roll is seldom adequate to span your entire roof. Where one roll meets another, you have a seam. The seam can be sealed up and made waterproof using chemicals or heat. 

Commercial roofers routinely hand-check every seam during annual inspections. 

Single-Ply

Single-ply roofing is one of these three types of thin, rugged material:

Single-ply roofing is not built up on the roof. It is a long-lasting plastic bonded to a scrim, a fiberglass mesh for strength. Single-ply roofing has far fewer seams than built-up roofing (BUR) or modified bitumen (Mod-Bit). It can be ballasted or mechanically adhered. 

Underlayment

The whole goal of a low-slope roof is to shed water and keep the building’s interior dry. A layer of natural or synthetic felt, or a self-adhesive rubber, called underlayment, can be used atop the substrate to add an extra layer of protection. 

For steep-slope commercial roofs, your commercial roofer will probably also recommend a water and ice shield, a thicker, tougher material laid down in the first three to six feet of a roof’s lower edge, as an even greater barrier to ice dams and water infiltration. 

When you make Damschroder Roofing your partner in protecting your commercial roof, you have an experienced ally familiar with all types of roofing materials, all methods of installation, and all maintenance scenarios. Please contact us today to learn more about our extensive services available to you, from roof coatings to complete tear-off and reroofing.