Cavity wall or External wall insulation - what is better?

21 Jul 2004
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United Kingdom

So which one is better in terms of insulation? EWI onrcavity with PIR insulation?

Is there any regulations that says that a new extensions to existing property can't have external wall insulation instead of a cavity wall?

EWI would require a building of a single wall in 140mm concrete block. Then you could go with 200mm EPS outside. The whole building is nicely wrapped from outside, so no chance of any damp coming in.

Cavity you have to build 2 walls but insulation gets put in at same time rather than added labour/time of doing it from outside for ewi.

But which type of construction is better? And can you have EWI on your neighbours side? More prone to damage probably if they decide to put something against it or kids kick the boards, might be a disadvantage.
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