Insulation in cavity

mikegc · 3 Feb 2016

Hi,

I am currently putting in a new bathroom. We had to take the window cill off (it was actually some hardboard with tiles and the plastic over the top).

Under the sill you can get into the cavity wall which shows some 25mm insulation. I was thinking of adding more where I can, it won't be much as there are bits of cement poking out of the brickwork. I was also going to use squirty foam between the window and the wall as I can feel a draft coming in.

Is this all worth doing before I put a new sill on? Should I do anything else to help keep the room warmer?

Thanks

foxhole · 3 Feb 2016

The draught will be from under the window where you have removed the inner sill.

mikegc · 5 Feb 2016

There is cold air getting in from between the window and the bricks which would be going into the cavity wall. I was thinking of using some expanding foam to plug up the gap, but worried about the expansion of the upvc in the summer.

Burnerman · 5 Feb 2016

You can do as you wish without worrying about any expansion problems.....but of course with the new cill in place the draught should go too.
Do make sure water cant penetrate under the new frame though.
John

phatboy · 6 Feb 2016

Expanding foam will bridge the gap between the blockwork skins, which could lead to damp from outside getting all the way through. I would just fix a new window board (cills are outside!) and it will be fine.

chappers · 7 Feb 2016

or if your really still concerned drop a cavity closer in first, by all means seal any gaps around the window though

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Insulation in cavity

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