PVC roofing systems are a time tested and battle proven system, first introduced in the US in the 1970’s and used often on flat and low slope roofs. It has some similarities to TPO, with the advantage being that it’s been around longer and the systems have been more refined. It also performs much better against corrosive chemicals like grease. Here in Arizona, PVC is a durable, reflective roof that is durable against the sunlight, heat, and UV rays, costs a bit more than TPO, and still has great warranties from manufacturers. It does well in all areas of Arizona, from Tucson and Phoenix to the mountain regions of Prescott and Flagstaff.
ABOUT PVC
PVC roofing is a type of single-ply membrane that is commonly used in combination with insulation board, such as polyiso, taper board, and a coverboard. This combination not only protects the insulation but also provides a smooth surface for the membrane. The insulation board also enhances the R-value of your ceiling and roof insulation, which is essential for meeting the energy code requirements in your specific climate zone. By combining the reflective properties of the PVC membrane with the insulation board, roofs in Arizona can achieve optimal energy efficiency.
There are many different suppliers and manufacturers of PVC membrane, including Carlisle Syntec, GAF, Duro-Last, and many smaller brands. PVC also comes in different thicknesses, including 45mil, 60mil, and 90mil. The thickness can correlate with a longer life. We recommend using a minimum of 60mil if possible, from a reputable manufacturer such as one listed above. These companies have been manufacturing PVC for decades and their products have stood the test of time compared to new manufacturers, which is important here in Arizona where we experience extreme heat in areas like Phoenix and Tucson, lots of powerful sunlight across the entire state, large variations in temperature, and even snow in areas like Prescott and Flagstaff.
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PVC roofing is a good choice on almost all commercial buildings, but particularly restaurants with grease hoods venting to the roof. Grease can be corrosive to other types of roofs like TPO, but PVC is able to withstand the effects of grease build up.
THE PVC ROOFING SYSTEM IN ARIZONA
There are multiple layers involved in the construction of a typical PVC roof, each playing a crucial role in ensuring a durable and long-lasting roofing system.
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In Arizona, when installing a PVC roof, the first step is to inspect the roof deck and ensure its structural integrity. Following this, insulation boards are securely fastened to the deck. In most cases, new construction plans in areas like Phoenix, Flagstaff, and Prescott specify R-30 insulation, which typically consists of two layers of insulation board, each approximately 2.6″ thick, depending on the manufacturer. The method of fastening the insulation board may vary based on factors such as the manufacturer, engineering specifications, wind rating, and more. However, it is essential to securely attach the insulation board to the roof deck using screws and insulation plates.
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Depending on the existing slope of the roof and its framing, a taper board may be required across the entire roof or only in specific areas. The taper board acts as an additional layer of insulation and is designed to facilitate water drainage towards scuppers or roof drains. It generally slopes at a rate of 1/4″ per foot. Proper drainage is crucial, and the taper board becomes particularly important when there is no existing slope or if the roof is sloped incorrectly. At M&M Roofing, we collaborate with our preferred manufacturers to develop a comprehensive drainage plan tailored to your roof’s needs.
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Subsequently, a coverboard is installed on top of the taper board. The coverboard is a thin sheet of material, typically measuring 1/4″ to 1/2″ in thickness. Its purpose is to provide a protective layer over the insulation and taper board, preparing the surface for the membrane application. The coverboard can be an additional layer of insulation board with a higher compressive rating or a fiberglass-gypsum material known as DensDeck board. Regardless of the specific material used, the coverboard serves to safeguard the insulation, enhance the membrane’s durability, and provide a smooth and sturdy surface for the membrane installation.
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Once all the aforementioned layers are in place, the roof is ready for the PVC membrane. PVC membranes are available in rolls ranging from 5′ to 12′ in width. There are two primary methods of application: mechanically fastened and fully adhered. In some cases, a combination of both methods may be employed.
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A PVC system that is mechanically fastened is installed over the coverboard, and then secured along the seams using screws and large washers. The next roll is then overlapped to cover these screws and washers, and the seam is heat welded to ensure a completely waterproof system. This process is repeated for the entire roof.
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On the other hand, a fully adhered system is utilized when there are higher wind ratings to meet or when a more durable end product is desired. In this system, a special adhesive is applied to the coverboard, and then the PVC membrane is rolled over the adhesive. Once the adhesive sets, the roof system remains firmly in place. Similar to mechanically fastened systems, the seams are heat welded to create a continuous roofing system.
LIFESPAN AND WARRANTIES
When opting for one of our preferred manufacturers, we have the opportunity to acquire a manufacturer’s extended warranty directly from them to safeguard your roof. These warranties, commonly referred to as No Dollar Limit warranties or NDL’s, provide coverage for your roof for a duration of 20 years or more. In such instances, the manufacturer will dispatch a representative to inspect the installation of our roof, ensuring that it adheres to their specific requirements. Additionally, they may conduct some tests before issuing the warranty certificate. Although these warranties incur a slight additional cost to the overall project, they offer peace of mind, particularly when obtained from a reputable and well-established company.
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In general, if a PVC roof is installed correctly and with high-quality materials, you can anticipate a lifespan of approximately 15-30 years here in Arizona.
ABOUT M&M ROOFING
M&M Roofing has been installing PVC low slope roof systems across Arizona since 1984 . We service the entire state, including Tucson, the Phoenix metro (Queen Creek, Gilbert, Chandler, Phoenix, Tempe, Scottsdale, Glendale, Goodyear, Avondale, Peoria and outlying areas), Prescott, Flagstaff, Kingman, and everywhere in between. Give us a call to schedule a free consultation.