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Single ply membrane: TPO (Thermoplastic Polyolefin) |
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Single ply membrane: EPDM (Elastomeric membranes) |
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Single ply membrane: PVC membranes |
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Mastic Asphalt |
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Built-up felt |
Key issues
• Embodied energy - there's a wide scale of embodied energy from wood shingles at the low end of the range to aluminium at the high. The main energy components are those derived from manufacture and transport. As with other materials, sourcing a product in the UK (and close to site if possible) can dramatically reduce its embodied energy.
• Material efficiency - Selecting a material can be made more complicated once its efficiency is considered. For example in some circumstances it can be argued that a strong, lightweight material used over a large span can have a lower environmental impact than a heavier, more sustainable material once the degree of structural support is introduced into the equation.
• Durability - The longer lasting roofing material has a lower environmental impact.
Materials
Single-ply membrane: TPO (Thermoplastic Polyolefin)
Closely-associated with other thermoplasic elastomers, thermoplastic polyolefin elastomers (TPOs) are two-component elastomer systems consisting of an elastomer (such as ethylene-propylene-diene monomer or EPDM) finely dispersed in a thermoplastic polyolefin (such as polypropylene) where thermoplastic polyolefin is usually the major component.
TPO's usage has spread from the car industry and since around 1990 had been making steady inroads in construction until the last few years when it's expansion accelerated when its superior environmental credentials became more recognised. TPO roofing membranes differ from EPDM membrances in that they are easily heat-weldable and, allegedly provide greater resistance to chemical and biological attack
