It is relatively new in the roofing market but has a high return for its cost. EPDM is a synthetic rubber while TPO is a rubber-like plastic. Lightweight, completely waterproof, resistant to punctures and tears and highly flexible (important when considering the temperature fluctuations of winter and summer). TPO also is available in white colour resulting in a highly reflective surface that can save you heating and cooling costs. Some manufacturers of TPO roofing materials also market it as “seamless” due to the hot-air welded seams – a much stronger alternative to adhesives.
TPO is typically based on polypropylene and EP (ethylene-propylene) rubber polymerized together using state-of-the-art polymer manufacturing technology. This technology enables the production of TPO membranes that are flexible at low temperatures without the use of polymeric or liquid plasticizers.
Unlike some other popular thermoplastic roofing membranes, the TPO polymer does not contain chlorine and no chlorine-containing ingredients are added during sheet production. This lack of chlorine allows TPO marketers to advertise their membrane as an environmentally safe, “green” product.
The TPO resin is compounded with other components including a weathering package, fire retardants and pigments for color to create a product that can withstand the elements associated with rooftop exposure. Sheet are available in varying widths up to 3.66m and membrane thickness is typically 1.1 or 1.5 mm although membrane up to 2.0 mm is also available.
If you are not sure what type of roof you have, or if you are in need of a repair, give us a call.
For more information on the many different types of roofs visit Roof Maintenance.ca.
TPO is a “Cool Roof”
A cool roof has two factors that need to be explained: reflectivity and emissivity. Reflectivity describes the amount of solar energy that is reflected back by the roofing membrane into the sky. A white membrane would reflect the most while a dark membrane would reflect much less. Emissivity is basically a measure of how well the membrane can shed heat. For example, a white surface will repel the most heat while a black surface will absorb the most.
The higher the emissivity and the higher the reflectivity of the membrane, the more energy efficient the design. Thermoplastic roofs have the highest reflectivity and emissivity values, explaining why they have increased in market share so substantially in recent years and are becoming great alternatives for Toronto commercial buildings.
In a thermoplastic system, seams are all welded with hot-air. Field seams are performed using a “robot” that fuses a consistent 1.5” weld while details (flashings) are done by hand with handheld hot-air welders and seam rollers. Due to the permanent nature of this type of seam, major manufacturers will commonly allow the finished roof to have small ponding areas and still be eligible for a strong guarantee.
TPO roofing systems offer a fire-resistant membrane that is essentially comprised of two plies of thermoplastic that are laminated together with a polyester reinforcement to strengthen the bond. The membrane is also resistant to chemical and grease. Other traits of TPO roofing systems include a more puncture-resistant and durable surface than EPDM, allowing for more rooftop traffic. TPO roofing systems can also easily repaired using TPO patches, certain coatings, and repair tapes.