Am looking to dot n dab an external solid 9" wall and am unsure as to whether I need to use vopour control foil backed board or standard plasterboard.
The external face of the wall is insulated rendered, so in theory there should be no instance of cold air meeting warm on the inner wall surface. This tends to sway me towards using regular board.
Is this correct?
moderately, but I would still use foil board.
The price differential is not great.
Dot and dab doesn't stick to foil backed so it'll fall down unless you can find a way of introducing mechanical fixings.
Fair point..
Is there no adhesive that will stick to the foil?
You may be ok. I used insulated plasterboard (9mm p/b with approx 40 mm expanded polystyrene) dot n dabbed on my 9" walls. A small bedroom with 3 external walls showed signs of moisture - darkening of plaster skim on boards - 'cured' by foil backed lining paper.
Aren't you required to use insulation backed board? If you modify the wall don't you have to insluate it right up to part L? In any case, it is desirable. A small sacrifice of room size makes an enormous difference to the heat loss. IIRC 30mm celotex bonded to 12mm PB takes a 9" wall from a U value of 1.8 to 0.3 (W/sqm/K).
Robert
Yikes, I really didn't want to read that. I've just done all of my outside walls with this stuff. How soon was it before the problem showed up and where did you get the foil backed lining paper from?
I would not use dot & dab on external solid wall ... I would batten and fit a avapour barrier (or foil face)
Have something to add? Share your thoughts — no account required.
Ask the community — no account required