PVC (polyvinyl chloride) Vinyl (PVC) is the best known thermoplastic roof membrane. “Thermoplastic” means that when heated sufficiently, the material temporarily changes from a solid to a semisolid state enabling the sheets or panels that are overlapped to be fused together a nd return to a solid upon cooling.
| RubberBond FleeceBack EPDM |
PVC Flat Roofing | |
| Is the product available only to trained installers? | Yes. Installers have to undergo a two stage training course and regular site inspections to meet & maintain approved status. |
Yes. Installers are trained for use in these products. |
| Cost. | Though the products have comparable material costs, the slower installation times of PVC flat roofing systems often lead to higher installation costs. | |
| UV Resistant. | Yes. EPDM membranes are manufactured to be UV stable and keep this ability throughout it life time. |
Initially, but the migration of the plasticisers in the product caused by UV exposure reduces its life time. |
| Strength. | With a strong polyester fleece laminated to the underside of the membrane this gives a strong puncture free material. RubberBond FleeceBack EPDM is supplied in one thickness for all roofs as we believe all flat roofs domestic or industrial deserve the best. | PVC membranes are available in a range of thicknesses or finishes. Materials with reinforcement added give comparable strength results. Non reinforced membranes give lower results. It all depends on the type used in the installation. |
| Can it be repaired? | Yes. The membrane can always be repaired or added to. There is no evident loss of ability to join or repair. |
As plasticizers migrate, PVC membranes can lose pliability and consequently, their ability to be effectively heat welded. |
| Shrinkage. | None. | Yes, but this is controlled with the use of base ties at angle changes to stop tenting of the membrane (Base tie ins are mechanically fixing the membrane to the deck to secure it) |
| Ponding Water Damage. | EPDM membranes perform well under ponding water conditions. The only downside, as with all single ply membrane, is the visual aspect of ponding water. | Ponding water can have a three-fold detrimental effect on conventional PVC roofing membranes. Ponding water will magnify UV to intensify its effects. The “water” is often a concentration of chemical discharge and environmental fallout throughout the roof system. The concentration of these chemicals can accelerate plasticizer migration. Eventually, algae can form, feeding on the plastisol and eventually the membrane itself. |
| Quality. | Factory Applied Tapes on the membranes allow for fast, effective seaming of sheets where most of the work is done in the factory and not by the labour on site, giving more quality control to the finished flat roof. | The seaming of sheets is carried out on site by means of hot welding. This is a slower process and reliant on the skills of the roofer. If the membrane gets too hot the sheet will become brittle, too cold and the seam will not be water tight. This can be affected by as little as one part of the roof being in sunlight and the other in shade. |