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What is a TPO Membrane?

More roofing definitions

Thermoplastic polyolefin membrane (TPO) is a thin, pliable covering installed on a structure to protect the roof against all types of weather. It is made from a mixture of rubber and plastic which combines the beneficial properties of both. The most important benefit of TPO membrane is that sheets can be joined together using a hot-air weld to provide a seamless roofing cover. This material is particularly popular with flat roofs or those that are highly visible such as domes.

How TPO Membrane is Manufactured

TPO roofing membrane is manufactured using petrochemical-based materials (polypropylene and ethylene-propylene) combined to create a flexible sheet. A weathering formula and fire retardants are added to the resin to enhance its weather- and fire-proofing qualities. The roof-covering material has three layers: a TPO-based top and bottom with a reinforcing fabric sandwiched between the two to provide additional strength. TPO is a relatively new product and therefore changes are still common. ASTM specification D6878 for Thermoplastic Polyolefin Based Sheet Roofing was in development as recently as 2003.

TPO is sold in sheets that are one hundred feet long and vary in widths between five and twelve feet. It is manufactured in light colors - beige, white, tan, and grey - as these reflect light better and reduce the amount of heat absorbed by the membrane which would be transferred to the structure.

Installing TPO Membrane

TPO membrane can be installed using either mechanical fasteners and plates or adhesives. In the first option, the plates are installed along the edge of the membrane and the fasteners are pushed through both the membrane and the plate into the roof decking. In the case of adhesives, the membrane is glued to the insulation (that has already been fastened to the structure) or directly to the deck material.

Warranties on TPO Membrane

Manufacturers' warranties cover properly-installed TPO membranes for 20 years although some limit this coverage to commercial buildings. Homeowners should check with their roofing professionals to determine which brand of TPO membrane will be used and what warranties the manufacturer offers.

Common Problems

Poorly installed TPO membranes or defective adhesives can cause the roof cover to buckle or bubble. Poorly glued or fastened seams will allow water to seep in causing leaks into the roof structure. Material failures in the late 1990s and early 2000s led to a number of manufacturers pulling their products off the market to reformulate the resin used in the making of the membrane.

Environmental Impact of TPO Membrane

As TPO is a petrochemical-based product, its main impact on the environment occurs during the oil-extraction process. TPO membrane, however, uses a low amount of materials, has a long lifespan, has low energy demands in its manufacture, and can easily be reused or recycled. The material is 100 percent recyclable during the production process as it can be chipped, melted and reused to manufacture new membranes. TPO polymer does not contain chlorine and no chlorine-containing ingredients are added during the manufacture of the membrane.

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