Ivan Zrilic of Ardex Australia discusses the reasons for the steady growth in the use of single-ply thermoplastic polyolefins (TPO) roofing membranes in Australia.
When it comes to choosing the type of roofing membrane to install on any low-slope roof, a number of factors come into play, including the type of roof itself (whether it is new or a retrofit), existing surfaces, surrounding elements, warranty requirements and, of course, the client’s needs. For more than 40 years, traditional multilayer bituminous sheets have been used and this type of technology has served its purpose, albeit with little or no technological upgrades during that time. However, we are beginning to see new systems introduced into the market and we only have to look overseas to see how popular it can become in such a short space of time.
When we take a closer look at what’s happening in the US and Europe, we can see a shift in usage patterns from multilayer bitumen towards single-ply thermoplastic membranes. Single-ply thermoplastic polyolefins (TPO) roofing membranes have been used extensively in international roofing installations over the past 15 years and its use has grown exponentially during this period. In the US market, TPO systems now constitute 28 percent of the roofing membranes market. In Europe, TPO roofing membranes are on the rise because of the ability to install under a wide range of weather conditions. Over 150 million square metres of TPO roofing membranes are produced throughout the world each year and with more and more countries realising the benefits, this figure is on the rise.
The reason for this growth internationally is three-fold: it offers technological, ecological and safety benefits.
The installation of traditional multilayer bituminous sheets requires the use of naked gas flame on building sites, which is becoming more and more unfavourable as it is deemed a serious health and safety issue. Using multilayer bitumen systems can add additional weight bearing on the roof structure. Labour time is also significantly greater as two layers of membrane are generally required to complete the installation. The quantity of seams is also higher because of the use of smaller sheet sizes.
TPO is a proprietary thermoplastic polyolefin combining polypropylene and ethylene rubber. It is quick to install and safe to use due to the application process involving hot air welded seams and water-based materials to adhere the product. Utilising a non-flammable, non-hazardous system, TPO membrane is extremely safe with no risk of fire or risk to health. Hot air welding eliminates the need for any naked flames on-site for the installation.
The hot-air welded seams result in a fully secure consistent seam quality of high strength. Heat welded seams form a homogeneous bond by fusing the top and bottom sheets together. This seaming process enables it to be installed all year round in a variety of weather conditions – one of the reasons it has become so popular overseas.
TPO membranes are lighter in weight and easier to handle than bituminous sheet membranes. While flexible, they have a rigid feel and tend to hold their shape well. There are a variety of widths and installation options available for low-sloping roofing applications in both refurbishment and new construction projects.
With the building industry constantly looking to reduce its carbon footprint, TPO membranes offer a more environmentally friendly option, as they have a lower production footprint than comparable systems and they can be easily recycled. White TPO has one of the lowest GWP (Global Warming Potential) values of 30 kilograms of carbon dioxide compared to bituminous membrane of 81.8 kilograms of carbon dioxide per square metre of installed membrane.
TPO membrane possesses an outstanding resistance to shrinkage and cracking from UV (ultraviolet) radiation and ozone exposure due to the fact that it contains no plasticisers, heavy metals or halogenated flame retardants. The stable inert formula component provides many years of durability as an exposed membrane in the Australian environment.
While these membranes are normally used in fully exposed situations, they can also be covered with self-supporting toppings under adhesive fixed tiles, landscaping materials or other finishes such as synthetic grass adhered directly to the membrane.
Due to its benefits, the TPO membrane usage in residential to large-scale commercial roofing in Australia is likely to follow the market trends in both the US and Europe.
Ivan Zrilic is product manager – waterproofing and flooring of Ardex Australia.