In the UK, there are five broad categories of single-ply roofing:
1) Poly-isobutylene (PIB)
This polymer was invented by chemists working for the BASF chemical company in 1931. Thus, PIB is the oldest single-ply roofing material in the world and is often regarded as a benchmark material for single-ply applications. One major advantage of PIB is that it has attained the standards ISO14040 as determined by the international standard organisation (ISO). It means that PIB has no major environmental impact and it is 100% recyclable. In addition, PIB is highly impermeable, durable and will withstand chemical corrosion and long periods of inclement weather. An added bonus is that PIB sheets are flexible and are relatively easy to install.
2) Thermoplastic Polyolefin (TPO)
These polymers were developed in the 1980’s and are in some respects more environmentally sound than PVC. The initials TPO cover any material that contains a synthetic polymer and filler such as fibreglass which strengthens the entire structure. TPO is used in a range of civil engineering applications including lining for artificial ponds and for waterproofing tunnels. The material is tough strong and durable with a wide range of applications but is only partially recyclable. TPO is only available in grey and can only be installed by heat welding. In addition the welding can only occur if the sheets are kept very clean. In turn they can only be kept in such a condition by regular washing with solvents, which of course undermines their environmental credentials.
3) Thermoplastic Poly-olefin Elastomer (TPE)
In effect TPE is the improved version of TPO and as such is the preferred of the two substances. It is completely recyclable and can be installed without welding meaning that the need for specialist (and more expensive) contractors is reduced. TPE is easier to clean and maintain and can be repaired by gentle heating of minor damage, whereas both TPO and PVC would require patching.
4) Poly Vinyl Chloride (PVC)
PVC is the third most used synthetic polymer in the world and is by far the most utilised single-ply roofing material in the UK. PVC is available in a very wide range of colours and styles and is easily installed and welded. Furthermore, PVC contains plasticisers and chlorine and if combusted will produce dioxins, which are highly toxic to both humans and animals. It also important to be aware, that PVC cannot be laid over substances such as bitumen without an isolating and / or waterproofing layer.
5) Ethylene Propylene Di-ene Monomer (EPDM)
EPDM is a semi-elastic synthetic rubber material which is very common in residential roofing applications. It is often made to measure and the joining, welding and attachment points are assessed off site. When brought on site the material is further sealed and treated to the requirements of the premises. Overall, EPDM is inexpensive but only available in black and must be treated to meet requisite standards of fire safety.
Clearly, it is essential to consult with professional contractors before deciding on the correct materials for any premises.