Recently, there has been an increase in the use of single-ply membrane roofing systems on the flat and low-pitch roofs of warehouses, distribution centers, and commercial buildings in the UK. The two most common types of single-ply membranes are TPO and PVC. Both PVC and TPO offer a durable, weldable, waterproof roofing system which means that they can be installed with very little disruption to the normal operations of a business. However, TPO and PVC differ with respect to their long-term performance. Selecting the less appropriate product on a particular building can lead to increased long-term costs or even premature roofing failure.
TPO: Lightweight and Cost-Effective
Thermoplastic polyolefin, also known as TPO, has become a popular option for large commercial roofs because of its cost, flexibility, and reflectivity. The white or light grey surface of TPO reflects solar heat which can reduce cooling loads in warehouses and industrial units during warm weather. Plus, TPO is lighter than many alternatives, which can be a critical factor when dealing with older commercial buildings that have weight restrictions on the roof decking.
PVC: Built for Chemical Resistance
Unlike TPO, PVC has been proven reliable, and has gained respect for its resistance to chemicals. PVC is more oil and grease resistant making it the more rational long term investment for food processing and manufacturing plant operations. These often have higher initial costs than TPO, but are long lasting and more economical.
Seam Strength and Long-Term Durability
Another area of divergence is seam strength. Both materials are hot-air welded, which means that when done correctly, seams are usually stronger than the membrane itself. However, due to the chemistry of the PVC, it is able to hold weld integrity for a longer period in more severe environments. This is important for commercial and industrial roofs that will be exposed for decades to plant equipment, foot traffic from maintenance crews, or RTU units.
Weighing Up the Cost
While costs are important for roofing contractors, they usually consider other points, other than costs. What other considerations are there? Starting off, TPO, or thermoplastic polyolefin, and PVC, or Poly Vinyl Chloride, are two options usually presented to roofing contractors. Of the two, TPO is regarded as significantly less expensive and therefore more desirable for large distribution warehouses because of the large total roof area. PVC prices, on the other hand, can be justified as they meet more demand.
Fire Performance Matters
The fire safety performance of a roofing material is also important, especially for commercial buildings with stringent insurance or building control requirements. PVC possesses good fire-retardant properties due to its chlorine content, while TPOs tend to have disparate fire safety performance results from various manufacturers. Therefore, for any given roofing material to be used in a commercial project, it is essential to examine the third-party fire test results to ascertain how well a given TPO formulation performs.
How Long Will Either Membrane Last?
When a qualified commercial roofing contractor installs each membrane and they are properly maintained with routine inspections, the longevity of both materials can reach twenty years or more. Additionally, the most significant risk to the lifespan of either type of membrane is not due to the materials, but rather poor installation. This is why the installation experience is just as important as the decision to use either TPO or PVC.
Which One Suits Your Building?
For standard warehouse, retail park, and light industrial projects without unique chemical exposures, TPO presents a solid and economical option along with real energy-saving advantages due to its reflective surface. Where business premises deal with chemicals, oil, or grease during day-to-day operations, or where there is a fire performance priority due to underwriters or building code regulations, PVC may be a justified extra cost.
Get a Proper Survey First
No matter which membrane is suitable to a specific commercial or industrial building, the best way to avoid expensive surprises down the road is getting a complete survey and definitive specifications before construction begins. A qualified commercial roofing contractor will evaluate the existing deck, usage of the building, drainage needs, and any future rooftop equipment before suggesting one system rather than the other.
Leave a Reply