thermoplastic membranes: PVC & tpo

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Thermoplastic single-ply membrane roofing systems are often used on commercial roofs and have some distinct qualities. We’ll talk about what this material is, why it works well for commercial structures and whyr you should consider this type of roofing material.

What is Thermoplastic?
The material differs from thermosets (EPDM) in the fact there is no chemical cross-linking.  It is distinguished solely for its repetitious ability to be cooled and reheated.  The seams of this material are typically heat welded with either solvents or hot air.  The material comes in several subcategories, which include:
  • PVC, or polyvinyl chloride, are calendared, extruded or spread coated while being reinforced with scrim, polyester or distinct glass fiber mats.  They range in sizes, usually 6-12 feet wide and 45-90 mils thick.  Gray and white are the most common PVC membrane colors.  It provides excellent weathering characteristics, high tensile strength and long-term flexibility. It also exhibits excellent resistance to harsh chemicals and industrial pollutants.
  • PVC Alloys such as Tripolymer Alloys, Nitrile Alloys, Ethylene Interpolymer or Copolymer Alloys make up the compounded thermoplastics, commonly known as PVC Alloy.
  • TPO, or Thermoplastic Olefin, are similarly calendared to PVC yet are lamination-based in manufacturing.  Two different polymers, polypropylene and ethylene propylene, are forged into sheets with polymer added to backing.  They are flame-retardant, UV absorbent and are stronger than most other Thermoplastic membranes.  It is designed for use in mechanically fastened and adhered roofing applications in new, re-roof and re-cover roof constructions.
  • Chlorinated Polyethylene
  • Polyolefin
PVC and TPO are the most commonly used thermoplastic membranes due to their material qualities, although some applications will use the latter two.

Why It Works Well
Many hot and dry climates favor this material because of extreme concentration of ultraviolet rays constantly beaming down on the roof.  Whereas tar-based roofs can radiate heat inwards since it lacks UV-blocking properties, Thermoplastic membranes generally carry much stronger UV protection which reflect the UV rays back up.

Would This Material Work For My Commercial Roof?
General practice is to apply thermoplastic sheets to flat roofing structures since they’re not particularly flexible on ridged roofs.  If your industrial, commercial, retail or institutional roofing system is flat and needs something that will block the sun’s damaging rays along with having cost-effectiveness in mind, this material would work perfectly for you.  RPC personnel are experts in thermoplastic roofing materials and can suggest the correct application on a per-client basis.