What is a TPO Roofing System?

Many building owners have heard of TPO.  But do you really know what it is and what goes into a TPO commercial roofing system?  With TPO being one of the most popular roof systems, we explain the fundamentals here.

Thermoplastic Polyolefin, known as TPO, is a commonly used roofing material that is also one of the newest in the industry. Introduced in the early 1990s, the single ply roofing membrane is energy efficient, lightweight, and easier to install than traditional flat roof systems.  TPO is a single ply membrane system which is very competitive when compared to other single-plies like EPDM and PVC roofs.

TPO roofs are very solar reflective.  This gives building managers greater control over the interior temperature on those hot, sunny days.  This makes TPO a popular choice for industrial facilities which are hard to cool or have no air conditioning at all.

What Goes into TPO Roofing Systems

For more information regarding TPO roofing systems, contact the professionals at Reliable Roofing

The TPO “system” consists of the membrane, a cover board and/or insulation, TPO accessories, TPO compatible metal, and TPO compatible adhesive or fasteners.  All must be approved by the membrane manufacturer and properly installed in order to qualify the manufacturer’s total system warranty.

TPO membrane comes in a variety of thicknesses.  Typical thickness is 45, 60, or 80 Mils (a mil is a thousandth of an inch). For a 20 year guaranty, a 60 mil membrane is the norm.


The TPO membrane can be applied in 3 ways: fully adhered with bonding adhesive; mechanically attached; or mechanically attached just at the seams.  TPO is always heat-welded at the seams and at accessories.  Heat welding creates a monolithic bond between sheets or from sheet to accessory.  This is fast and easy method of seaming is what gives TPO its edge over other systems.

As with all installation, properly following the manufacturer’s spec is crucial.  For example, a mechanically attached sheet which is not done correctly, may allow wind underneath and billow.  Seams that are not welded at the proper temperature may look tight only to pop at a later date.  Many people consider fully adhered to be the best application method because it is no subject to billowing and the effects of a popped seam are mitigated by the adhesive.


TPO can be applied on a variety of substrates.  Most manufacturer’s allow application directly to polyiso insulation.  Many specify a coverboard depending on the application and the needs of the specific building.


The typical mandated energy rating for new installations is R-30 where the insulation is provided above the roof deck. This means 5.2 inches of polyiso insulation.  Again, the insulation must be installed according to manufacturer’s spec in order to meet the warranty requirements.  Insulation is most often mechanically fastened, but can be adhered using adhesive foam.  The foamed application is significantly more expensive.

Cost of a TPO Roof

Because of its standard accessories, light weight and comparatively easier (“easier” is a relative term in commercial roofing) installation process, TPO is a very cost-competitive system.  A simple recover with few rooftop penetrations and a basic metal specification can be as inexpensive as $4.5 per square foot.  Actual price varies according to numerous factors, including geographic location, the roofing contractor, seasonal conditions, roof top complexity, etc.).

Get a total system warranty!

Flat roofs leak.  It’s not “if”, but “when”.  Insist on a total system labor and material warranty that covers leak repair.  See our blog on not all warranties are created equal.

Work with Reliable Roofing

Licensed and insured, Reliable Roofing technicians are trained to install and maintain your TPO roof with efficiency and speed. We partner with top manufacturers to consistently ensure only quality materials are utilized in every roofing project. Manufacturer specifications are followed to make sure your roofing project is completed with precision.

Get a Free Estimate

Reliable Roofing proudly serves the Chicagoland area with commercial roofing services. Give us a call at (815) 981-9898 to receive your free estimate on one of our services.