TPO Membrane

A relative newcomer to the field single ply roofing: TPO or Thermoplastic Polyolefin, has been around since the late 1980’s.

TPO membranes are produced by calendering with lamination, extrusion with lamination, or extrusion-coating techniques. TPO sheets are a blend of polypropylene and ethylene propylene polymers and usually are reinforced with polyester scrim. TPO sheets contain colorant, flame retardants, UV absorbents and other proprietary substances to achieve desired physical properties.

Early formulations of TPO had reports of accelerated decomposition of the membrane in areas where additional sunlight would reflect off a surface onto the TPO. However, many manufacturers insist that either their membrane never suffered from these issues or their formulation has been altered to alleviate the problems.

TPO Membranes are fastened in one of 3 ways:

• Mechanically fastened assemblies rely on rows of screws or nails to secure the membrane to roof deck.
• Fully Adhered assemblies use special glues to ensure the membrane stays stuck tight to the insulation.
• Loose laid assemblies are not fastened to the roof deck but rather are covered in smooth river rock whose weight ensures the membrane does not blow away.