Insulated plasterboard on a bay wall

15 Dec 2008
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United Kingdom
Hi I'm trying to decide how best to proceed with a bay wall that had some penetrating damp. There was a large curved radiator fitter to the wall - as it is a solid wall construction I'm also keen to improve the U-value.

The house is a 1934 semi-detached and the mortar is quite crumbly so I was going to have the wall sand and cement rendered to increase the water resistance and also deal with the crumbly nature of the existing mortar.

I was then planning to attach insulated plasterboard using adhesive foam. I could then have the plasterboard skimmed.

Using this system would hopefully:
  • Stabilise the crumbly mortar - plenty of sand found in the floor void which I assume has come from the wall over the years.
  • Improve the resistance of the wall to penetrating damp - it's a solid wall so vulnerable to this.
  • Improve the U-value through the use of the insulated plasterboard.

This is the wall:

View media item 108078
I'm not a builder. These suggestions have come from the internet and I'm hoping that someone here has some experience with such a solution.

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15 Oct 2021
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United Kingdom
i’d remove the loose mortar and render over with 4:1 sand /cement with waterproofer. Then tank the whole area. next do your thing with insulated pb and skim.
i’d cut the cills back to the brickwork first and fit deeper pvc cills at the end.

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