Thermoplastic materials are distinguished from thermoset materials in that there is no chemical crosslinking. These membranes can be repeatedly softened by heating or hardened when cooled. Because of the materials' chemical nature, thermoplastic membranes typically are seamed by heat welding with hot air or solvent welding.
Thermoplastic Olefin (TPO)
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. TPO sheets contain colorant, flame retardants, UV absorbers and other proprietary substances to achieve desired physical properties.
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. TPO sheets contain colorant, flame retardants, UV absorbers and other proprietary substances to achieve desired physical properties.
- Sheet widths range from 6 feet to 12 feet wide
- Sheets are typically 40 mils to 100 mils thick
- Seams are sealed by heat welded with hot air
- TPO membranes commonly are white
Material standards
NRCA does not make any recommendations about which TP product or manufacturer to use; however, NRCA does recommend that TP products meet standards established by ASTM International.
NRCA does not make any recommendations about which TP product or manufacturer to use; however, NRCA does recommend that TP products meet standards established by ASTM International.
- ASTM D4434, "Standard Specification for Poly(Vinyl Chloride) Sheet Roofing"
- ASTM D6878, "Standard Specification for Thermoplastic Polyolefin Based Sheet Roofing"
Warranties
When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof membrane. Please read NRCA's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.
Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.
When purchasing a new roof system, there will be two warranties to consider. First, there will be the manufacturer's warranty. In general, these warranties cover defects in the manufacture of the roof membrane. Please read NRCA's consumer advisory bulletin addressing roofing warranties for more information. Once the project is complete, be sure the contractor provides you with a certificate for your records.
Second, the roofing contractor will provide you with a warranty covering his workmanship. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one year or two years of coverage; however, there is no industry standard.