What is Tpo?
TPO is an acronym for thermoplastic-polyolefin. Let’s break down what this means to us in a roofing context.
Thermoplastic: Much like the name Veritas, plastic in this context brings us back to Latin class with the word plasticus, meaning able to be molded. Thermo-plastic: able to be molded when heat is applied
Polyolefin: TPO is made of a polyolefin rubber called ethylene propylene rubber, or EPR for short, a polymer containing useful properties such as heat resistance, weather resistance, strength, and flexibility. This EPR is reinforced with a fabric component, often polyester, to increase its durability and impact resistance.
The science behind TPO matters in a roofing context because its properties make it the best solution for low slope commercial roofs in North Texas.
Installed as the “membrane,” TPO is used as the exterior waterproofing surface of a low slope roof system. Unlike more common “built-up” system comprised of multiple layers of asphaltic based materials, TPO is considered a “single-ply” roof system, consisting of just one layer of material.
What are the benefits of a TPO roof system?
TPO is light-weight, flexible, durable, impact-resistant, environmentally friendly, and safe to install.
Light weight & flexible
North Texas property owners know how buildings can shift with moving foundations, and a TPO’s flexibility allows it to maintain its function even if your building’s foundation is moving. TPO is flexible enough to allow for the installation of the membrane to curve upward and continue on to perimeter parapet walls and curbs for HVAC connections on top of your building. This benefits the roof because there is one continuous membrane waterproofing the structure.
Durable & impact resistant
These roofs have proven more than capable of standing up to the test of North Texas weather. In fact, TPO is tested in the manufacturing process under extreme conditions that will never present themselves on earth.
Manufacturers will place a segment of TPO in a heat-aging oven at temperatures above 200 degrees Fahrenheit for a period of up to a year and will then test that the material does not crack when bent around a steel pipe.
TPO is also tested against accelerated weathering by putting a sample through a process called xenon-arc testing, where the TPO endures ultraviolet and infrared radiation, ozone, and moisture exposure to simulate years of outdoor weathering. The TPO is viewed under a magnifying glass to check for cracks in the material.
In addition to these tests, this robust material is also put through cycles of various extreme conditions, including heat aging, followed by submersion in near-boiling water, next followed by xenon-arc testing, through multiple cycles to simulate repeated extreme changes in conditions.
Simply put, TPO is the best commercial roof membrane for long term durability against North Texas’ severe changes in weather. These systems can stand up to the extreme Texas heat, heavy rains, and even hail!
TPO’s heat resistance and other chemical properties gives it an environmental advantage over traditional asphalt-based roof systems. The polyolefins used in TPO are recyclable and non-hazardous. This material’s heat-resistance and sunlight reflectiveness allow commercial buildings to consume less energy, thus lowering air conditioning costs. Many brands of white TPO qualify for LEED certification points and are ENERGY STAR compliant.
The installation process of TPO does not require the use of open flames, so no noxious fumes are emitted, and there is no risk of spills of hot asphaltic liquids.
A safe and reliable installation process
As mentioned in the previous section, these installations are much safer than the installation process for more traditional asphalt-based roof systems.
TPO is stored and transported in rolls with widths of 6 to 10 feet and lengths of up to 100 feet.
These rolls are laid out on top of insulation boards, are mechanically attached to insulation layers and the roof’s decking using fasteners, and then are heat-welded using electric machines that apply hot air to meld the seams together (remember: thermo-plastic!).
Compare this process to asphaltic flat roofs that require propane torches or hot kettles of boiling liquid tar – no thanks, not on my building!
As aforementioned, these systems are easy to maintain and repair over the life of the roof. If you plan to add new tenants in the future, a TPO system can easily be modified to accommodate additional HVAC units, skylights, or other utility penetrations as needed. These roofs are easy to clean, and with proper maintenance and seasonal work will last as long as needed.
Veritas Roofing’s best practices energy-efficient TPO roof system
At Veritas Roofing, we are proud of our ability to update and upgrade old structures into code-compliant, energy-efficient buildings.
Veritas Roofing’s best-practices TPO solution is an intensive re-build of a roof from the decking up. Many cities in North Texas require re-built roofs to be brought up to a recent version of the International Energy Conservation Code (IECC), and most often, older roofs are lacking in the insulation r-value.
When your roof has inadequate insulation, it will cost more to heat the building in the winter, and cost more to air-condition the building in the summer.
When Veritas Roofing re-builds a commercial roof, our preference is to remove all existing roof layers down to the roof’s decking, which is the structural flat surface that a roof is installed on top of.
Most roof decks are made of steel, although some older buildings still have wooden decking. After all the old materials are removed, where applicable, a vapor barrier may be installed, followed by layers of insulation, then next if applicable a cover board, and last the TPO membrane.
Veritas Roofing commonly installs two layers of 2.2” thick ISO board (short for polyisocyanurate). ISO is a plastic product produced as a foam that hardens in its final form. This hardened foam is layered between two sheets of glass fiber reinforced felt facers. ISO layers are mainly flat boards; however, ISO is also manufactured in slanted or tapered boards, used to direct the flow of water on the roof towards drains and/or gutters to prevent ponding water on the roof.
The ISO boards are secured to the roof deck using fasteners and fastener plates, with the membrane secured to the ISO in a similar fashion. ISO boards are commonly 4 feet wide and 8 feet long and are available in varying thicknesses. After reviewing the r-value requirements of your city’s building code, Veritas Roofing will determine the appropriate thickness of ISO and the proper number of layers of ISO to install to satisfy code requirements.
While this is Veritas Roofing’s preferred roof system, building owners can still reap the benefits of a TPO roof system even if a full rebuild does not fit the budget.
Alternatively, Veritas Roofing can install retrofit or overlay, TPO systems whereby a coverboard is secured on top of an existing roof system, with brand new TPO installed on top of the coverboard. While this option does not provide as significant of a boost in r-value as a complete rebuild with ISO, the building will still benefit significantly from the overlay TPO membrane.