If you are looking to install a single ply roofing membrane that will be energy efficient and are evaluating your options, consider TPO (thermoplastic olefin) roofing. TPO is touted to have the benefits of two of its direct competitors EPDM and PVC roofs, but without the drawbacks and extra costs. This means that a TPO roof is as UV-resistant and as heat-resistant as EPDM, and as heat-weldable as PVC. As any roofing material, TPO also has its disadvantages and shortcomings that are primarily due to the fact that TPO is a fairly new roofing material on the market and research still continues to find the most durable and long lasting product formulation. Before purchasing a TPO membrane for your home or commercial building, carefully consider all the pros and cons of TPO roofing.
We recommend that you read our overview of MRCA TPO Advisory (from 2010) which it has issued for commercial roofing contractors, and what it means for building owners.
What is TPO?
The TPO membrane was first introduced to the roofing market in the early 1990’s as a more economical and efficient alternative that was thought to replace PVC roofing products. TPO is a single ply roofing system that consisting of a thermoplastic polyolefin membrane. This membrane is composed of three layers:
1. TPO polymer base.
2. polyester-reinforced fabric center (scrim).
3.thermoplastic polyolefin compounded top ply.
Common fillers used in TPO manufacturing include but are not limited to: talc, fiberglass, carbon fiber, wollastonite, and Metal Oxy Sulfate. Popular rubbers used in TPO manufacturing include ethylene-propylene rubber and EPDM.
Benefits of TPO Roofing
One of the factors that makes TPO roofing attractive both in residential and commercial construction is its reasonable cost. TPO offers many of the same benefits as PVC roofing, such as hot-air weldable seams and energy efficiency, but at a lower cost.
Fits different home styles
Many homeowners appreciate the fact that TPO is manufactured to look great on many different types of homes. TPO is available in white, light grey and black reflective color options. Now you do not need to get a white roof to enjoy the energy saving and reflective properties. Latest technologies enable all colors of TPO roofing membranes to be UV resistant and “cool”.
In comparison to other thermoplastic membranes, TPO resists mold growth, dirt accumulation, tears impact and punctures. It is made to be flexible and can allow for a home’s or building’s movement or settling. Reinforced TPO membranes can handle a building’s thermal expansion and contraction more effectively than other single ply roofing products.
Ease of installation
In general TPO membranes are manufactured with wider sheets and are light weight. This means that the material is easier to install and there is less seams. Less work and time associated with the installation translates into direct savings for you for the cost of installation.
The energy efficiency of TPO roofing membranes makes them highly attractive to home owners who want to have the benefits of savings on their ocooling costs as well as help the environment by reducing the carbon footprint. TPO’s membrane’s white reflective surface exceeds the EPA’s ENERGY STAR requirements and white, tan and gray are listed with the Cool Roof Rating Council. This means that having a TPO roof on your home or building will keep the interior thermally comfortable on hot summer days while reducing your air conditioning costs.
Disadvantages Of TPO
One of the biggest disadvantages of TPO is that it is a really young roofing technology. It has been around only for about 10 years and manufactures are still trying to figure out the best chemical formula that will make the product durable and long lasting while maintaining a competitive price. Finding this right formula has been a challenge for many manufacturers and over the years there have been many documented instances of seam failures and material failures such as membrane curing and cracking. New and improved formulas continue to be tested, but it is not possible to tell at this point how long a new TPO roofing product will last. If you choose to purchase a TPO roofing membrane, it is advisable to get it from a manufacturer that has been around since the beginning of TPO production, as they will most likely have the most long lasting formulation available on the market today.
Does not stand up well to heat load
TPO roofing membranes have been noted to have an issue of accelerated weathering when subjected to high thermal or solar loading. This problem has been specifically documented in the Southern states that get a lot of heat and sun throughout the year. The MRCA committee that issued the report based on their research, recommended the following to contractors: “If situations exist that may commonly elevate temperatures over 160 degrees or increase solar loads beyond “normal” question the manufacturer as to the suitability of their product for the situation; consider changing the product to a material that will clearly withstand the loading.