As a commercial roofing contractor, you're not always involved in the single-ply membrane selection process. However, when a client asks for your advice on a project with specific needs, it can be reassuring to know you have some solid options.
For projects with unique requirements – for example, a high level of resistance to grease, chemicals, or UV radiation – PVC roofing stands out among other single ply membranes in the industry.
What is PVC?
PVC (Polyvinyl Chloride) is a thermoplastic, developed in the 1960’s and introduced to the U.S. in the 1970's. A PVC roof membrane consists of three layers – a top and bottom layer of PVC, and a middle reinforcing layer (or scrim) made of either polyester or fiberglass fibers. Like other thermoplastics, PVC membranes can be heat welded, forming a strong, monolithic, watertight barrier.
PVC roofing membranes utilize a liquid plasticizer, which contributes to their superior flexibility. However, liquid plasticizers can eventually migrate out and evaporate, leaving the membrane brittle and prone to cracking over a long period of time. The chemical composition of a high-quality membrane like GAF EverGuard™ PVC includes phthalates, which improve membrane strength and long-term membrane longevity.
PVC KEE (Ketone Ethylene Ester) is a specialized PVC formulation developed in the 1980s. PVC KEE utilizes a solid plasticizer, which does not evaporate over time. This gives the membrane superior durability and longevity – defining characteristics of GAF EverGuard™ PVC KEE.
Both GAF PVC and PVC KEE utilize a polyester scrim, which gives the membrane enhanced puncture resistance, tear strength and flexibility.
Performance Advantages of PVC
PVC roofing is known for these outstanding performance characteristics:
Durability and Sustainability
GAF PVC membranes have superior resistance to UV radiation and heat, and have earned a Cool Roof rating from the CRRC (Cool Roof Rating Council). During testing, GAF PVC roofing membranes are subjected to concentrated UV rays, high humidity and heat that replicate real world conditions. GAF PVC and PVC KEE membranes have been proven to exceed ASTM G154 and G155 weathering test standards by as much as a factor of 7x. This commitment to exceeding industry standards can give clients confidence in the membrane's long-term reliability even beyond the typical warranty period.
By also incorporating high-performance biocides, GAF PVC membranes resist the growth of fungus and mold, which can cause stains and "hot spots" that absorb heat and reduce the reflectivity and energy efficiency of the roof. This is particularly important on roofs with high-SRI (Solar Reflectance Index) requirements.
GAF PVC and PVC KEE offer excellent warranty protection, depending on membrane thickness and type. PVC membranes offer guarantees ranging from 15 to 30 years, while PVC KEE guarantees range up to 35 years for select systems.
Fire Resistance
GAF PVC roofing membranes meet the UL Class A fire protection designation when tested in accordance with ASTM E108, and they have a lower flame spread than EPDM or TPO membranes.
Grease Resistance
PVC roofing is highly resistant to animal fats, grease and vegetable oils, to a much greater degree than other single ply membranes. This makes it an excellent choice for restaurants and food manufacturing facilities.
Chemical Resistance
PVC offers excellent resistance to a broad range of chemicals, including acids, chlorine, gasoline, jet fuel and other petrochemicals. It is ideal for roofs at airports and gas stations where the roof may be subject to traces of gasoline or jet fuels. Its resistance to acids and chlorine make it a superior choice for schools, natatoriums, scientific labs, or chemical manufacturing plants.
Flexibility and Convenience
Due to their combination of plasticizers and polyester reinforcement, GAF PVC membranes are known for their ability to flex and conform to roofs with curves or complex geometries.
This flexibility and strength allows contractors to form roof accessories onsite using PVC and PVC KEE roof membranes. Or, to save valuable time, you can opt for a number of GAF labor-saving prefabricated accessories, including pipe and vent boots, corner and curb wraps, scuppers and sealer pockets.
For quick PVC repairs, GAF has a line of aerosol cleaners, primers and adhesives which are portable, easily applied by one person, and ideal for small repairs or in awkward spaces.
PVC offers many installation options, capable of satisfying requirements from wind uplift to puncture resistance to the need for quick installation:
Mechanical Attachment
Using GAF Drill-Tec™ fasteners and plates, mechanical attachment is one of the fastest installation methods in a wide range of temperatures. Heat-Welding the end and side laps to ensure a water-tight seal gets the building in the dry fast in combination with this method. It is easy to identify a PVC or PVC-KEE membrane that has Heat-Welded seams as membrane bleed-out will be a visible indicator.
Adhered
GAF PVC and PVC KEE membranes can be adhered to the substrate using Traditional Bonding Adhesive, or for quicker installations, Water-based Adhesive, Low-rise Foam, Quick-Lay* Adhesive and Quick Spray Adhesive are recommended. They all result in a uniform, smooth appearance, minimize membrane uplift and thermal drift, and help the membrane act as a vapor barrier.
The use of fleece-backed PVC membranes is recommended for roofs requiring increased puncture resistance, on rough-textured substrates, and on hybrid roofs where separation between the PVC membrane and the asphaltic roof assembly below is required.
(*It should be noted that Quick-Lay adhesive is not currently compatible with PVC KEE membranes)
Induction-Welded
Induction welding is recommended on projects that require a quick dry-in period, with minimal uplift or membrane billowing. There is no cure-time, fumes or messy cleanup, and this method has the widest range of recommended installation temperatures. Heat-Welded Side and end laps is common practice with this method of installation.
When choosing or recommending a single-ply roofing membrane, rest assured that GAF provides PVC options for every situation. If you’re looking for a membrane with high resistance to chemicals or animal fats, excellent fire resistance, and durability against UV radiation and heat, a PVC or PVC KEE roofing membrane can both protect your client's investment and minimize your time and labor costs.
Find out more at GAF PVC Roofing Resources or email GAF’s Building and Roofing Science Team at brsteam@gaf.com or GAF Design Services at designservices@gaf.com with any questions.
