March 14

Considering a TPO Flat Roof

TPO or PVC | What’s the Difference and best place to use each?

If you are in the market for a new commercial roofing system.  You start talking with a roofing contractor and he begins with throwing around terms like PVC and TPO. How do you translate that into what flat roof works better for your organisation?

Many business owners and property managers have this problem when beginning a new roofing or re-roofing problem below we will try to simplify the myths and terminology and describe the pro’s and con’s of each.

What they have in common is Single-Ply Membranes

Both TPO and PVC are single-ply membranes.  As single-ply membranes, they are best suited to flat or low-slope roofing structures, though can be used on other styles.  These thin sheets of material are laid on top of the existing roofing system and may be connected to that system either chemically with adhesives or using mechanical fasteners.

Single-ply membrane systems offer specific benefits to building owners.

See below

Cool Energy which is Efficient.  Single-ply membrane systems come in a wide array of color and reflectivity levels.  The more reflective the material, the more the sun’s heat is reflected away from the building.  The reduced heat can lead to savings of up to 40% on air conditioning costs, depending on location in Ireland. Usually cost effective in big shopping centers, tesco and pennys are example of the shops that would have this product installed.

Flexible.  The flexibility of the membrane system is important.  This flexibility allows for flexing and contraction as temperatures rise and fall and contributes greatly to the durability of the product.

Lightweight.  Designed with specific weight regulations in mind.  The lightweight nature of single-ply membranes contributes to the amount of weight to the overall structure.

Low Maintenance.  Most single-ply membrane systems are designed to be low maintenance, requiring little more than annual inspection and basic preventative maintenance.

TPO Pros and Cons

TPO is made from rubberised materials, generally a blend of polypropylene plastic and ethylene-propylene rubber.  The sheets come in various thicknesses, ranging from 40mm to 100mm with the most common for roofing applications.

TPO is manufactured primarily in 6’ to 12’ widths.  Sheets are rolled out on the roofing and cut to fit the widths of the roof.  They are then secured to the roof in 1 of 2 ways:

  1. Using nails, screws or anchors that attach to the building.
  2. Fully adhered utilizing an adhesive material.

To reduce the risk of moisture getting into the seams, and to prevent seam separation, the seams are then generally heat welded or glued together to produce a primarily monolithic or one-piece system. Check with your individual flat roofing contractor to see what way they apply the finish

Benefits and drawbacks of TPO

TPO membrane systems offer specific benefits to their building owners.

  • Less expensive than PVC.
  • More chemically resistant than PVC.
  • Better for the environment than PVC.

However, there are some drawbacks.

  • TPO is a newer material on the market, so there is less experience regarding longevity and durability.
  • Less fire-resistant than PVC.
  • Quality variations between manufacturers.

Lets talk about PVC Flat Roofing

PVC is the one of the most used and produced synthetic plastic in the world.  In its original form, it is the rigid white plastic that you would be familiar with in plumbing and other applications (ducting pipes) etc.  With added “plasticizers”, it becomes the workable version used in single-ply membrane systems.

This single-ply roofing ranges in thickness from to 50ml to over 100ml, depending on manufacturer.  It comes in rolls of widths from 6’ to 12’ rolls, with different sizes available from other specialised manufacturers.

PVC and TPO are very similar in application, usually chemical adhesive, mechanical fasteners, or ballast.

Listed below are the benefits and drawbacks of PVC

PVC membrane systems have significant benefits.

  • More time on market, resulting in better information regarding durability than TPO.
  • More fire resistant than TPO.
  • More resistant to puncture and weathering than TPO.

PVC also has a few distinct drawbacks.

  • Slighlty more expensive than TPO.
  • Shrinks over time.
  • May be difficult to repair as it ages.

Conclusion

Selecting your contractor is actually as important as selecting your material.  The installation process, the quality, seams followed when installing a single-ply flat roofing system. Read our guide to selecting the best flat roof system


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