Single Ply roofing membranes provide a variety of materials to choose from. Their main characteristic is that they are designed to be installed in one layer. They also exhibit great flexibility and their resistance to UV radiation is superior when compared to other products. It is usually black or white finish, and glued, fastened or installed directly over the roof insulation.
Single-ply membranes can be generally categorized into two groups – thermosets and thermoplastics.
- Thermosets, or those materials that you can’t hot-air weld (EPDM) because it will change their physical characteristics, use a tape or a contact cement to make up the lap.
- As opposed to thermosets, the seams on thermoplastic single-ply membranes can be hot-air welded together to form cohesive laps. When thermoplastic membranes cool, they return to their original material type. PVC and TPO are two of the most commonly installed thermoplastic single-ply membranes.
Types of Single ply membrane
PVC (Polyvinyl Chloride)
Due to its durability, longevity and ability to withstand a build-up of chemicals, PVC is a widely used flat roofing system. PVC is also extremely easy to manufacture, install and repair. PVC membranes are manufactured from a combination of PVC resin, stabilizers, pigments, fillers, plasticizers, biocides, and various processing aids. Unlike TPO membranes, which require additives to increase fire resistance, PVC membranes are naturally fire retardant.
TPO (Thermoplastic Olefin)
Much like PVC, Thermoplastic Olefin is another commonly used material for a wide variety of flat roofing solutions. Due to the strong weatherproofing properties, TPO is often used when undertaking a green roof construction and has a life expectancy of around 20 years. TPO can be installed in a multitude of ways and with the introduction of peel-and-stick products, installation time can be reduced significantly. Like PVC, TPO remains hot-air weldable throughout its service life, simplifying repairs and maintenance.
EPDM (Ethylene Propylene Diene Terpolymer)
EPDM is a versatile and flexible single ply material that can be mechanically secured, ballasted as well as fully adhered. EPDM has excellent weathering qualities as it is 100% resistant to UV radiation, Ozone thermal shock and changing weather conditions. EPDM membranes are known for their long-term weathering ability and perform well even when subjected to fluctuations in temperature, ultraviolet rays, and ozone. The membranes are available in both unreinforced and reinforced, the latter of which increases resistance to tearing. EPDM is available in thicknesses and is offered in wider sheets that may be desirable.
Fastening Single Ply Roofing
In a fully adhered system, the membrane is bonded or glued to the substrate. Typically, in these assemblies a layer of insulation is mechanically fastened to the structural deck, however, it can also be glued, depending on the deck type.
The majority of the single-ply materials are mechanically fastened to the structural roof deck using screws and “plates” or oversized washers designed for the application.
By contrast, ballasted systems use stone or paver materials to hold the roofing membrane in place. The roof cover is loose laid over the insulation, which is either mechanically fastened or loose laid in place, and then ballast is installed on top.
Rather than relying exclusively on in-seam fastening techniques for mechanically attached thermoplastic membranes, another alternative option is induction welding. The system, called RhinoBond, is a non-penetrating option for installing TPO and PVC membranes. RhinoBond is a proprietary roof attachment system approved for use by select roofing manufacturers. The system requires the use of RhinoBond Plates and OMG manufactured fasteners, as well as a RhinoBond welding tool.
Proper Installation and Maintenance are Critical
Regardless of the roofing system you choose, proper installation and regular maintenance (including regular inspections) is a must. When searching for a roofing contractor, make sure the company you hire is experienced and trained to install single-ply roofing system. Using a qualified roof consultant can significantly help with the process and help eliminate problems. Contact SMC Group for more information at (416) 731-7737