insulating single skin for bathroom

13 Apr 2013
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United Kingdom
hi i am converting a single skin (3 sides) coal shed with pre cast concrete flat roof into a bath/shower room.

what is the best way to insulate the walls, floor and ceiling to insure no damp, etc.

i figured for the walls making a 100m stud inside, filling with 100mm celotex, etc. plasterboard and skim, then tile finish.

same for the ceiling but without tiles.

is this suitable? do i need a vapour barrier also?

advice appreciated.
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ok thanks, so is this all i need to use?

i work for a timber merchant so timber, celoxtex and plasterboard, etc is cheaply available so would ideally like to go down this route.
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I Don't see a problem with what you propose, make sure you tape over all the stud work with foil tape to create a vapour barrier or staple a VP to your walls before you fix your plasterboard.
You are likely to get cold bridge 'shadowing' unless you fix some insulation across the studs also, prior to fixing the plasterboard.

The most recent job we did asked for a further 40mm across the timbers.
ok thanks noseall.
so can i fix plasterboard straight onto the celotex?
do i need an air gap at all?

sorry real beginner here.
No need for an air gap, though it would be prudent to use foil backed (duplex) plasterboards.

Have you given any thought to the roof insulation?

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