When confronting a commercial roof replacement project, selecting the most appropriate roofing system can seem complicated and confusing. There are so many material and assembly options available for low-slope roof applications, making choosing difficult. Therefore, it is important that you receive guidance from a qualified professional that can educate you on the pros and cons of each type of roof, suitable for your building. Today’s most commonly specified assemblies for low-slope re-roofing are Single-ply and Modified Bitumen systems.
Single-ply
Single-ply membrane systems represent approximately 85% of the low-slope commercial roofing market. A Single-ply roof system is one in which the principal roof covering is a single layer of flexible membrane, often a thermoset rubber (EPDM) or thermoplastic (TPO, PVC). Single-ply membranes can be installed in a variety of attachment configurations, most commonly ballasted, mechanically attached, or fully adhered. Thermoset sheet seams are glued together to create a continuous waterproofing membrane. They offer excellent weatherability and impact resistance, good extreme weather flexibility, and low installation, maintenance, and life-cycle costs. As Thermoset systems age they may experience reduced thickness and shrinkage, which can contribute to failed seams and membrane tearing under stress.
Thermoplastic sheet seams are welded together using heat to create a continuous waterproofing barrier. They offer extreme heat and UV resistance, excellent tear strength, good puncture resistance, are recyclable, and offer no surface food source for mold or algae growth. As Thermoplastic systems age, small cracks can develop on the membrane surface and they can sometimes grow more brittle.
Because of the fact that Single-ply systems offer only one thin layer of waterproofing protection, they are susceptible to damage from debris and rooftop traffic. Thankfully, the root causes of system performance issues can usually be easy to identify and inexpensive to fix.
Modified Bitumen
Modified Bitumen (MB) systems represent approximately 12% of the low-slope commercial roofing market. A MB assembly consists of composite sheets composed of bitumen modified with SBS or APP polymers to enhance performance and reinforced with Polyester or Fiberglass mats. Most Modified Bitumen roof assemblies are configured with one or multiple base sheets and a cap sheets. The cap sheets can be surfaced with films, foils, or mineral granules that provide UV protection and wear resistance. The systems are installed with cold process adhesives, hot asphalt, or by heating and melting the membrane with a torch. MB systems can be applied in hot and cold temperatures and perform well over their life in all climate zones. They are highly durable and exhibit exceptional tear and puncture resistance.
Modified Bitumen membranes provide excellent weatherability but over time the cap sheet’s surfacing is likely to deteriorate from exposure to the elements or excessive traffic. Resurfacing of MB systems can be done at a relatively low-cost, and is a good roof asset maintenance strategy. While more costly to install than Single-ply systems, Modified Bitumen assemblies are very commonly specified in institutional, healthcare, owner-occupied, and other high-value properties.
At Innovative Roofing Group, we spend a considerable amount of time asking questions of our customers about how they utilize their buildings and to fully understand the budget realities. We also closely investigate the current roof composition and condition. Finally, we incorporate local building code requirements when developing a system recommendation. For each application, we try to provide our customers with options to consider. Contact us today by calling 404-594-6038 to find out how we can help you.