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Earthwool insulation as wall cavity

Postby JazzQ » Sat Jun 13, 2020 7:28 am

I am having a single storey extension built and the builder has used 100mm Knuaf Earthwool insulation in the cavity wall instead of 100mm Rockwool insulation as specified in the drawings. I am annoyed at this because I understand rockwool is a better product and has better R value, fire resistant, better sound insulation. Its too late to rectify as the wall has already been built. Approx 26 square meter has been used. How much should I be looking to deduct from the final account now that I have a deficient wall insulation that wont retain heat for longer.
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Simply Build It

Postby stoneyboy » Sat Jun 13, 2020 10:19 pm

Hi jazzq
Probably easiest to ask your builder to increase the thickness of the insulation behind the plasterboard on external walls to compensate.
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