By Evelyn Witterholt.
For first-time or current building owners, making a roofing decision can be stressful, especially when you are unfamiliar with the types of commercial roofs on the market. Knowing even the basics of the different types of commercial roofs that are on the market can help you tremendously in the process. While a roofing contractor can help you with this, here is our complete guide to each type of commercial roof as well as their pros and cons.
Asphalt roofing has been a reliable choice for commercial roofing for over 100 years. The two main types of asphalt roofs are built-up roofing (BUR) and modified bitumen, but sometimes asphalt roofs will be a hybrid of the two. Although asphalt roofs are durable, they are not as long-lasting as metal roofs.
BUR systems are made of layers of bitumen, or asphalt, and roofing felts which are reinforced with mats. Together, these materials make a durable roofing material that can withstand stress and thermal shock for a long time.
Modified bitumen roofs are made of asphalt and polymers and, like BUR systems, they are applied in layers of modified asphalt. According to IKO, the two types of modifiers used in modified bitumen roofs are APP (atactic polypropylene) and SBS (styrene butadiene styrene) and most membranes are installed as a two- or three-ply system. These roof types are great because they can be applied in any climate and they withstand harsh weather elements.
Metal roofing has been on the rise in the industry for the last few years and for good reason. These roofs are made of highly durable materials such as aluminum and steel and are known for their long lifespans. Although they are pricier than other types of commercial roofs, metal roofs are resistant to wind, rain and heat. Commercial roofs that use metal do have to have a low slope of a minimum of ½ in-12 according to National Roofing Contractors Association (NRCA)
these are typically made from galvanized steel (steel coated with zinc).
A single-ply roof is a single layer of membrane material that is typically rolled over on top of the roof’s insulation and cover board and then fixed with attachments or an adhesive. Commercial building owners like this roofing material because it’s easy to install and cost-effective. Single-ply roofs are also resistant to peeling, cracking, puncturing and weather damage. The main types of single-ply roofing are thermoplastic polyolefin (TPO), polyvinyl chloride (PVC) and ethylene propylene diene terpolymer (EPDM).
TPO and PVC membranes are similar because they are both thermoplastic membranes, meaning they are made from polymers that react to heat by softening and to the cold by hardening. On the other hand, EPDM is a thermoset membrane that’s made from rubber polymers. Both offer the same benefits of being a relatively affordable commercial roofing option.
Liquid-applied roofing systems are typically made from asphalt or urethane materials. Liquid-applied roofs are also good for buildings that have open businesses because they don’t emit harmful odors while being installed. However, for them to function effectively, they must be installed properly with the substrate free from any dust or moisture.
While green roofs are rarely offered aren’t as common as these other roofing types, they are great for buildings that want a highly sustainable roofing option. Green or vegetative roofs are made from plants that are installed in trays on top of the roof’s surface. They can absorb rainwater to prevent runoff and make a nice space for building occupants to enjoy on top of their building. We see these green roofs most often on the roofs of schools or non-profit organizations.
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