Insulating Solid and Cavity Walls

12 Jan 2015
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United Kingdom
Our house is an old solid stone cottage that was refurbish in the 70s by the previous owners reusing the old ground floor walls, ~500mm thick, where they existed and adding a storey and a half extension upstairs of cavity wall breeze block. All of this has a pebble dash finish.

The big question is how to insulate the house. Do we treat it as if the entire structure is solid stone, therefore needing breathable materials or with different treatment upstairs and down?

Downstairs at present looks like, stripping off the plasterboard; insulating with wood fibre boards between the framing, then replacing with standard plasterboard and skimming with Gypsum. Upstairs we'd strap the external walls and use something like Kooltherm to board our and again skim with Gyspum.

Any help most welcome.
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I'm not a designer and have no clue about 500mm thick walls so can't specify in detail. However, insulating between framing may not be adequate. you may also need to insulate across the face of the framing also.

Breathable materials are not necessary. You just need to insulate robustly i.e. include vapour barriers where necessary and ensure that all joints are tight or sealed with foam, mastic or foil tape.

Have you thought about getting this designed?

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