Insulated plasterboard for bathroom with solid walls

[Pulp]

Hi,

I'm having my bathroom refitted in the new year but wanted to insulate the outside wall - it is a solid wall so was looking at something like Celotex PL4000 directly fixed to the wall. I'm looking to lose as little space as possible so was thinking about going for the 25mm insulation with board attached - overall 37.5mm. I'm a DIYer so would appreciate some pointers, firstly is this the type of product I should use, or do I need something with an 'aquapanel', is direct fix ok? Would 25mm be enough - bearing in mind curently there is nothing, and finally this will be tiled fully to 2m - the full height of the insulation - as it then has a slope on the ceiling.

Any advice appreciated.

Thanks

 

[23vc]

dab it on with the odd mechanical (screw fixing), go for insulation as thick as you are prepared to loose on the space.
Tank it before tiling if it's a shower which is an alternative, tho not as good as, cement board(aqua panel)

 

[endecotp]

You could consider Marmox; they are waterproof and you can tile onto them: http://www.marmox.co.uk/products/multiboard

Is this actually behind a bath/shower, or is it a drier position?

 

[Pulp]

Thanks both, bath will be against this wall. Don't want to lose more than a couple of inches, hence 25mm then board then tiles. Currently there is nothing, so thought this must be better than no insulation.

 

[endecotp]

In thermal terms, 25mm+12.5mm PL4000 is 0.83 W/m^2K; 40mm marmox is 0.90 W/m^2K. So very similar but the celotex is slightly better.

This will be much better than your current solid wall, but not up to current building regs requirements. To achieve that level I think you'd need to at least double the thickness.

I'll let others comment about best practice for waterproofing a wall in this position. I'd say "better safe than sorry".

 

[23vc]

Tank it whichever you use and all should be good. costs about 40 quid well worth it.

 

[Pulp]

Thanks for the advice, I'm thinking what about celotex 25mm with an aquapanel plasterboard - rather than the PL4000?

http://www.wickes.co.uk/Knauf-Aquapanel-Water-Resistant-Wall-Board-1200-x-900-x-12-5mm/p/207027

http://www.wickes.co.uk/Celotex-25mm-High-Performance-Insulation-Board-1200x2400mm/p/190545