When it comes to commercial roofing systems, building owners have lots of options. Some have been around for more than a century; others are more recently developed. Here’s a brief look at what’s available on the market today.
Built-up roofing (BUR) systems have been used in the U.S. for well over 100 years and are still commonly installed today. So-named because they are literally manufactured or “built-up” on the rooftop by the installing contractor, BUR systems consist of alternate layers or “plies” of liquid tar or asphalt and roofing felt or another synthetic fabric. They are typically covered with a final layer of gravel or other stone ballast to protect the roof surface from foot traffic, sun exposure and other weather events. They are also known as “tar and gravel” roofs.
Single-ply roofing has become an increasingly popular flat roof covering over the last few years. Single-plies are flexible sheets of synthetic membrane, produced in a factory and shipped in rolls to the jobsite.
Evolving from built-up roofing, modified bitumen roof systems were the first single-ply products to enter the commercial roofing market. They’re essentially manufactured from the same raw materials – one or more layers of asphalt “modified” with rubber or plastic materials plus one or more synthetic fabric layers. “Mod-bit” roofs can be installed using a variety of methods, such as hot asphalt, cold adhesive, self-adhered or torch. Torch-down roofing is becoming less common and is even prohibited in some areas because of fire risk.
Other single-ply roofing systems generally fall into thermoset or thermoplastic categories. Both types can be applied to the roof deck using ballasted, mechanically attached or adhered methods.
Thermoset membranes (commonly known as EPDM) are vulcanized materials; the production process involves the formation of cross-links between rubber molecules to provide membrane elasticity, resilience, tensile strength, and weather resistance. Once the material is produced and “set,” it can’t be softened by heat, so rooftop seaming of membrane panel sections and flashings requires adhesives, not hot air welding.
Thermoplastic membranes were introduced in Europe in the 1960s. Unlike EPDM, these products do not contain cross-linked molecules, so they do not “set” but melt and flow when heated. So, membrane sections can be hot-air-welded together during installation on the rooftop. The thermoplastic roofing market is basically divided into two segments: PVC and TPO, both of which have taken market share from BUR roof systems over the past 50 years.
PVC (polyvinyl chloride) roofing has been available in the US since the 1960s and has a solid record of performance on all types of commercial buildings throughout North America. PVC roofing provides fire, oil, and chemical resistance and high reflectivity, as well as excellent weathering in all climates. PVC membranes can be factory prefabricated, enable secure on-site membrane seaming across a wide temperature range, and remain weldable for years after installation.
TPO (thermoplastic polyolefin) systems have been on the market for more than 25 years, but most installations have been done more recently. TPO was developed to combine the flexibility and weather resistance of EPDM and heat-weldability of PVC. TPO is resistant to chemicals, dirt and rooftop debris build-up. It’s the fastest-growing and most-installed commercial roofing system in North America.
No matter what type of roofing system you choose, its ability to provide long-term watertight protection for your commercial building ultimately comes depends on the contractor’s ability to do the job effectively. Versatile Commercial Flat Roofing’s expertise is installing single-ply roofing systems on all types of facilities throughout Michigan. If you’re considering a roof installation or replacement, we would welcome the opportunity to discuss what Versatile can do for you.
