Commercial Roofing Applications and Key Membrane Materials Like PVC and EPDM
Commercial roofing applications come in a variety of different materials. Longevity, durability, and cost are the most common differentiators between each material, and help guide the final decision.
PVC, Single Ply EPDM, Modified Bitumen and spray-applied roof coating are all viable commercial roofing options that have unique advantages. It is best to look at each solution comparatively and make the best assessment based on your priorities.
The most commonly used commercial roofing application, PVC (polyvinyl chloride) is a layer of thermoplastic material.
Highlights of a PVC commercial application are its strength, durability, and lack of water permeability. PVC systems can withstand up to 300 pounds per inch, 100 pounds per inch heavier than the industry-recommended 200 PPI.
Along with its strength, PVC is more energy efficient because of its white color. A white roof helps reflect the sun, allowing for lower cooling costs. Lastly, with a life-span of 15 to 30 years, PVC roof longevity is also a benefit.
PVC roofing systems are a reliable choice and hold up well over time. One thing to keep an eye on during yearly inspections are PVC’s seams. Installed in seams and reinforced with heat, PVC roofing applications can eventually have a failure or gapping in these areas over time.
Another common roof type is EPDM (Ethylene Propylene Diene Monomer). Like PVC, a single ply application, EPDM commercial roofing membranes are made of rubber. EDPM roofing systems are popular due to their lower cost in comparison to PVC systems and good resistance to weather permeability. Installation of EPDM systems, even on large jobs, is easier than other roofing applications because of its installation method. Covering large areas with big sheets of material at one time make EPDM installation less labor intensive.
Like PVC, make sure to regularly inspect the seams of an EPDM roofing membrane. Over time bonded seams can weaken from weathering, which can lead to gaps and eventual water damage. EPDM rubber roofing systems are also dark in color, attracting a significant amount of heat and accruing higher energy costs. Due to this, EPDM roofing options might not be the best choice in a constantly hot or sunny environment. The longevity of an EPDM roof is 10-15 years but with regular maintenance and inspection can outlast those expectations.
Modified Bitumen roofing systems consist of an asphalt base, modified with polymers to enhance the elasticity and flexibility of the membrane. “Mod-bit” roofing applications are highly resistant to tears and punctures and hold up well to general foot traffic due to their multi-ply roofing design.
Something to consider when choosing a Modified Bitumen roofing membrane is the installation method. Installers lay the material out on the roof and heat treating the pieces into one layer with a blowtorch to create a seal. The use of an open flame can make the application more time intensive and risky. More recent advancements, however, have produced a peel and stick method. Mod-bit roofs can also attract and absorb heat, making them less energy efficient than other options.
Thermoplastic Polyolefin (TPO), a reflective single-ply roofing membrane consisting of a polypropylene and ethylene-propylene rubber combination, is one of the fastest growing on the market.
The major benefits of a TPO membrane are their relatively low cost and the reflective white surface that helps to limit energy expenditure within a building. Aside from its resistance to ultraviolet light, the durability of TPO means tears and punctures aren’t often a problem.
TPO installation methods include mechanically attached systems, where the membrane is connected via mechanical fasteners and fully adhered systems where the membrane is bonded directly to the insulation layer. Some issues have been noted with TPO systems, included accelerated aging or deterioration around the fasteners as well as membrane shrinking.
A recent innovation in flat roofing options is fluid applied systems. Many types of chemistries of fluid applied roof coatings exist in the market today. Silicone based, Polyurethane based, Acrylic based, SEBS or (Styrene Ethylene Butylene Styrene). This application’s significant benefit is its seamless application. This helps to create a water-tight barrier. In many cases, spray-on applications are added on top of current roofing membranes adding even more protection. Spray-applied applications also have energy benefits. Due to its reflective properties, spray-applied roofing systems can provide savings in building energy costs.
Consistent installation is one aspect to consider. If material isn’t applied with precision, gaps, thin coats or incorrect sloping can lead to pools of standing water. Outside of these concerns, spray-on roofing applications have many benefits.
When installing a new commercial roofing system, select a material based on your environment and priorities. Weighing these strengths, including their durability, longevity, cost and energy efficiency, will provide a solution that works best for both the building and the buyer.
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