In this guide, we'll discuss...
- TPO Systems
- Membrane Thickness
- Advantages and Disadvantages
- Repairs and Maintenance
- Finding a Contractor
Thermoplastic polyolefin, or TPO, is a single-ply membrane roofing material popular in commercial roofing applications and sometimes used in residential roofing.
It’s a single-ply membrane similar in many ways to EPDM rubber roofing, although TPO is quickly replacing EPDM as the go-to choice for commercial roofing applications across the country.
TPO roofing membrane is as durable as EPDM, if not more durable, and is hot-air weldable. The roofer is able to weld the seams of each TPO sheet together, providing an extremely strong seal to protect against the elements. The seal is actually stronger than the sheet of material itself.
As the interest and demand for energy-efficient and heat-reflective roofing systems increase, TPO roofing continues to provide resistance to overheating and ultraviolet damage while being an environmentally conscious roofing choice.
When comparing membrane thickness, it’s important to remember that thickness does not always equal a better roofing system. The product type and installation practice are just as significant a factor.
TPO membranes come in a variety of thicknesses, but the most common thickness is 60 mils.
An important feature to remember is that roofing membranes have a reinforced area placed near the center of the membrane material. This area is interlaced with a matrix of tiny threads. The more threads, the stronger the reinforcement, and the greater the durability of the membrane.
When a membrane is thicker, a certain amount of milage is above the threads, and the rest is added beneath.
The area above is called "the wearing surface"—the surface in direct contact with the elements. What’s often surprising to property owners is how little of the membrane is above the wearing surface. So in order to increase the wearing surface thickness, the overall thickness of the membrane must be increased a great deal.
It’s important to keep this in mind when comparing membrane milage, product material, and cost.
LEARN MORE: Understanding Built-up Roofing
TPO material comes in rolls up to 12 feet wide and 100 feet long. It’s available in white, gray, and black—white is the most popular due to its UV-protection properties.
TPO roofing membranes are installed one of four ways:
- Heat-welded — a propane torch welds the membrane to the roof
- Adhesive applied to the backing/decking — “glued” down
- Ballasted — membrane is loose-laid and several inches of ballast material (rocks, pavers, etc.) are applied over top
- Fastened down with screws or screw-like fasteners — most popular method
One of the main benefits of installing a TPO membrane is the hot air-welded seams. Its seam strength is 3x stronger than rubber roofs that use tape and 6x stronger than glued seams.
- Easy installation
- Welds easily and is very strong
- Flame retardant
- Energy Star rated – Reflects average of 80% of UV rays (white TPO)
- Resistant to algae and mold growth
- 100% recyclable
- Quality/reliability is still questioned by some due to its relatively short history. However, modern TPO roofing materials are quite advanced and reliable.
- 10 - 20-year lifespan is less durable compared to other flat roofing systems
The cost of installing TPO roofing depends on the size of the roof, the complexity of the project, and the quality of TPO to be used. Overall, TPO is an economical choice, with prices averaging around $4 to $6 per square foot, which is less than BUR and metal roofing and is comparable to EPDM roofing.
Another prominent factor to consider when weighing the cost of a TPO installation is its “cool roof” properties.
White TPO roofing is considered a “cool roof” due to its UV-protection capabilities, so it can help lower the cost of cooling the building in the summer. It’s something to consider when comparing pricing between different types of roofing.
A major benefit of TPO roofing is its weldability. This makes it easy to repair leaks originating from seams or punctures. You can weld TPO membranes over and over again without a loss in strength.
1) Clean the Roof
The first step in all repairs is to properly clean the surface. Dirt and other debris can contaminant any repair effort.
2) Heat Weldability
Most TPO repairs can be repaired with a patch because they’re heat-weldable. In order to make such a repair, you’ll need electricity, a hot-air welding tool, and patching materials.
According to ASTM, you can weld TPO seams together or patch up small holes in the membrane by using a hot air gun set to 1,000 degrees F. Heat along the seams at a rate of 12 - 14 feet per minute to achieve an airtight seal. This type of repair is best handled by a professional roofing contractor experienced in repairing TPO roofs.
3) Asphalt Mastic
Another option is to make a patch with asphalt mastic, which can be found at most lumberyards. This can keep water out until material matching the roof is available.
We recommend calling a commercial roofing expert for TPO roof repairs. You should investigate the problem to further understand your roofing system, but large repairs should be left to the professionals to avoid long-term damage and large costs down the road.
There are a number of reasons building owners should perform routine maintenance on their roofs, including:
1) Ensure Maximum Reflectivity
Keep the surface white to ensure the roof is providing maximum reflectivity and conserving energy costs
2) Clear Dirt and Debris
Clean routinely to ward off the accumulation of dirt and debris, which can lead to algae and other organic growth.
3) Deter Animals
Prevent the growth of food sources in order to deter birds and other animals from causing damage.
4) Reduce Chemical Build-Ups
Ensure chemical contaminants don’t build up and harm the membrane of the roof, reducing its longevity.
LEARN MORE: Residential Flat Roof Repair 101
TPO has exploded in recent years as the most popular commercial roofing material in the country. Roofing contractors have taken notice and many are now well-equipped to install and repair TPO commercial roofing.
The most critical factor affecting TPO roof durability and performance is its installation. Hometown makes it easy for customers to compare roofing contractors. You’ll have access to a variety of options and receive free quotes for your project.