There are primarily three types of insulation that are used in external wall insulation systems.
Expanded Polystyrene: This is a lightweight, cost effective, user friendly insulation. Kt has a relatively good insulation performance but is combustible and should not be used internally or on buildings over 18m in height (11m in Scotland) hence only suitable for low-rise housing.
Traditional EPS is white in colour however EPS used within external wall insulations sytems is enhanced with integrated graphite within its bead structure which results in a grey colour is depicted below. The high-purity graphite particles reflect radiant heat and significantly improves insulation capability, It's proven to result in a 20% improvement in r-value over traditional white EPS of comparible thickness.
Stonewool Insulation: Also known as "rockwool" or "mineral fibre" insulation. Although less thermally efficient than EPS or other insulation types they major advantage is the fact that it is non-combustible. In fact, stonewool insulation acts as a fire barrier, helping to slow down the rate of flames without contributing to the fire. It therefore has no restriction in its use - including on high-rise buildings of more than 18m /11m in height.
Mineral Wool systems have other benefits too. They provide a high level of breathability, the presence of fibres and moisture repelling compounds within the material help to wick moisture through and away from the substrate and they also provide high levels of acoustic insulation performance.
Phenolic Insulation: A much less common insulant these days is Phenolic Foam. Whilst it is highly thermally efficient it is combustible so is ideally used on low rise housing where space is at a premium. As it is combustible it should not be used internally or on buildings over 18m in height (11m in Scotland).
The table below provides a comparison of the insulation types.
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