thermoplastic Thermoplastic Membranes Thermoplastic Membranes thermoplastic

Material and system description

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.

There are five common subcategories of thermoplastic roof membranes.

  • Thermoplastic Olefin (TPO)
  • Chlorinated Polyethylene (CPE)
  • Polyvinyl Chloride (PVC)
  • PVC Alloys or Compounded Thermoplastics
  • Copolymer Alloy (CPA)
  • Ethylene Interpolymer (EIP)
  • Nitrile Alloys (NBP)
  • Tripolymer Alloy (TPA)

The most common thermoplastic roof   membranes are PVC and TPO. The following provides general descriptions of these   two systems.

Polyvinyl Chloride (PVC)

PVC sheets are   produced by calendaring, spread coating or extruding, and typically are   reinforced with polyester or glass-fiber mats or scrim. PVC sheets contain   plasticizers and stabilizers, as well as other additives to impart flexibility   and achieve other desired physical properties. Some membranes are available with   nonwoven fleece backing adhered to the underside of a sheet.

  • Sheet widths range from 6 feet to 12 feet wide.
  • Sheets are typically 45 mils to 90 mils thick.
  • Seams are sealed by heat or chemical welding.
  • PVC membranes are produced in numerous colors, though gray and white are the   most common.

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.

  • 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

PVC and TPO roof membranes can be installed fully adhered, mechanically attached   or ballasted. Most PVC and TPO membranes do not receive surfacings.