House insulation - ...
 

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House insulation - avoiding thermal bridging

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We're installing internal wall insulation (old house, solid brick walls) and from what I read a major problem can be thermal bridging, where you have a less insulated gap that gets cold, produces condensation and then you have a horrible mould problem, all the joists rot and the house falls down.

I'd like to avoid this, ideally...

The installer is a local plasterer, comes recommended but I doubt is an expert on insulation.

It'll be insulation backed plasterboard, stuck on all the external walls (after removing the old render/plaster back to brick).

My main concern is in the gaps between floors. How is this best avoided? Do I just take up the floorboards around the edge of the 1st/2nd floors and insulate the bit of wall there? With what? Glass wool stuff? Expanding foam?

Anyone have experience with this, or just good ideas?


 
Posted : 29/12/2022 4:02 pm
 ajc
Posts: 212
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You need to get the property assessed by someone that knows what they are doing. Don’t put foam backed plasterboard in a solid walled house with lime mortar. Breathable materials only in an old house and you will need to have a robust ventilation strategy at the same time.

But back to the original question, yes you will have a thermal bridge. You will need to insulate the inter floor area. You may well need a wufi calculation to work out if your joist ends are likely to rot. Don’t leave it to a plasterer to tell you what to do


 
Posted : 29/12/2022 7:46 pm

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