So, you’re 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 (I thought that was a term for pipes?) and TPO (some new brand of toilet paper?). How do you translate that into what product works best for you?
This is a problem many business owners and property managers face when beginning a new roofing quest. An understanding of the terminology used in the roofing industry is paramount before anyone can possibly begin to determine what works for them and how best to proceed.
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. Some of those benefits are:
Energy 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 30% on air conditioning costs, depending on location.
Flexible. The flexibility of the membrane system is a crucial component. This flexibility allows for flexing and contraction as temperatures rise and fall and contributes greatly to the durability of the membrane.
Lightweight. Every building is designed with specific weight limitation. The lightweight nature of single-ply membranes contributes a negligible 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 (thermoplastic polyolefin) is made from rubberized materials, generally a blend of polypropylene plastic and ethylene-propylene rubber. These sheets come in various thicknesses, ranging from 40mm to 100mm, with 45mm to 65mm being the most common for roofing applications.
TPO is manufactured primarily in 6’ to 12’ wide rolls. Sheets are rolled out onto the roofing surface and cut to fit. They are then secured to the roof in 1 of 3 ways:
- Mechanically fastened using nails, screws or anchors that attach to the building.
- Fully adhered utilizing an adhesive material.
- Ballasted using rock to hold the membrane in place (less common).
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.
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.
PVC Pros and Cons
PVC (polyvinyl chloride) is the 3rd most produced synthetic plastic in the world. In its original form, it is the rigid white plastic that you’re familiar with in plumbing and other applications. With the addition of “plasticizers”, it becomes the flexible version used in single-ply membrane systems.
This single-ply roofing system ranges in thickness from to 50ml to over 100ml, depending on manufacturer. It comes in rolls ranging in width from 6’ to 12’ rolls, with custom sizes available from some manufacturers.
PVC attaches to the roofing structure in the same manner as TPO, that is either chemical adhesive, mechanical fasteners, or ballast.
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.
- More expensive than TPO.
- Tendency to shrink over time.
- May be difficult to repair as it ages.
Most Important Consideration
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Selecting your contractor is actually more important than your material selection is. The installation process, quality of adherence, seam welds and how protrusion are addressed are what will make or break your single-ply roofing system.
Let us help you. Choice Roof Contractor Group is an association of roofing contractors that have met training qualification and are held to high levels of professionalism in order to maintain their membership.
Choice Roof Contractor Group was founded to give contractors a firm base of resources for their roofing company in order to provide better service to building owners and/or property managers. Call one of our representatives today at (800) 670-5583. We would love to assist you in finding your next roofing partner.