Insulating under a bay window - north facing wall

[mikeinthemidlands]

Hi all

This is my first post - I have been lurking for a while reading some very helpful threads.

I would be grateful of some advice on how to tackle insulating under a bay window in my bedroom.

Under the bay there's a stud wall (3x2) covered with lath and plaster but no insulation. The wall is north facing and due to how cold the wall is, mould has started to appear on the wall.

The outside has felt and then plastic cladding.

I've attached a picture of the wall:

View media item 26379
I was thinking of removing the lath and plaster, putting in some 75mm Celotex or similar then overboarding with some 25mm Celotex then plasterboard. Does this sound OK? Do I need a membrane of some sort?

Also, is it worth stripping off the plaster around the bay (the whole wall) to insulate the wall and plasterboard? If so, I want to make sure I don't loose too much space as the room is quite small already.

Thanks for reading!

Mikeinthemidlands

 

[^woody^]

Your proposed work is OK. No need for a membrane. Make sure the insulation is a snug fit with no gaps

No need to insulate around the ay unless you are having condensation/mould problems due to a cold wall

 

[mikeinthemidlands]

Thanks for your advice Woody.

I will just insulate under the bay as although the surrounding wall is quite cold to the touch - I've not seen any condensation/mould.

Mikeinthemidlands