What is Single Ply Roofing Membrane?
Single ply is a flat, synthetic polymer based roofing material that provides a waterproofing layer in a single sheet. Usually supplied in rolls, the material is either entirely homogeneous or contains a reinforcement layer. Sealed at the joints with heat, adhesive or mechanical means, it can be adhered, mechanically fixed and/or ballasted into flat, pitched or green roof systems. Single ply roofs are lightweight, flexible, cost effective, swift to install and safe, which makes them increasingly popular for both new build and refurbishment projects.
Benefits of Single Ply Membranes
- Over 50-year track record
- Low capital cost and cost in use
- Safe, rapid and clean installation
- A well-managed sector with its own Trade Association (SPRA)
- Suitable for new build and refurbishment applications
- Some products are available in a wide range of RAL colours
- Simple to repair and modify
- Variety of sustainability characteristics including zero life cycle impact.
Types of Single Ply Roofing Membrane
There are five main types of Single Ply roofing membrane available in the UK. They are:
- PVC (Poly Vinyl Chloride)
- EPDM (Ethylene Propylene Diene Monomer)
- TPO (Thermoplastic Polyolefin)
- TPE, (Thermoplastic Polyolefin Elastomer)
- PIB (Polyiso Butylene)
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- PVC roofing membrane – Poly Vinyl Chloride
PVC is the most popular single ply roofing membrane, making up around 80% of the UK market. Available in a wide range of RAL colours, it is flexible, simple to install and generally liked by contractors. The system is homogenous, and joints are welded by a heat gun. PVC cannot be laid over bitumen roofing without an isolating layer, so it is not ideally suited for refurbishment applications. It is also the only membrane in our list to contain plasticisers and chlorine.
- EPDM roofing – Ethylene Propylene Diene Monomer
EPDM is an elastic, synthetic rubber roofing membrane, commonly used in domestic projects, an EPDM roof kit can be made up off site with penetrations pre-installed. Otherwise, welds are taped and complex detailing is required to avoid water ingress into the edges of the membrane through capillary action. Cost effective, but only available in black, EPDM needs to be ballasted to receive a satisfactory fire rating for surface spread of flame.
- TPO – Thermoplastic Polyolefin
TPO, introduced in the 1980s, is seen as more environmentally friendly membrane than PVC. It is used heavily in civil engineering – for pond linings and tunnel waterproofing, where the absence of plasticisers is considered an advantage. Like PVC, it can be partially recycled into
other products such as walkway tiles. In the past its sensitivity to UV light was an issue, but better formulations have removed this risk and life expectancy is comparable. Unlike PVC, TPO is only available in a narrow range of greys. One problem with TPO is that it cannot be welded
when dirty and can be difficult to keep clean on site. A solvent is required to clean the membrane before heat welding, which can counteract the environmental advantages of using TPO.
- TPE – Thermoplastic Polyolefin Elastomer
TPE is a product developed to improve upon some of the characteristics of TPO. It is 100 recyclable and is very simple to install. In addition, unlike PVC and TPO, welding is successful across a very wide range of temperatures, making installation much simpler for the contractor.
TPE also has re-healing capabilities – small punctures can be resealed using the application of heat, where PVC or TPO would need to be patched.
- PIB – PolyIso Butylene
Developed in the 1930s, PIB is the oldest single ply roofing membrane in the world, and roofs exist that are still performing after 50 years. Made from Oppanol, the same polymer that is used in chewing gum and surgical dressings, it is 100% recyclable. PIB is the only membrane with a
full life cycle assessment to ISO14040, confirming the product has no significant environmental impact from cradle to grave. PIB membrane has a self-sealing edge making it simple to install.