Hi all Is it ok to to fix kingspan insulation boards directly on to the wall without having to use battons, and as these boards have a foil backing on them can i just fix plasterboard straight on to them without having to use a vapor barrier.
Having opened out a fireplace for decorative effect (no fire in it), I put Kingspan along the back, which was only single brick thick, to stop it getting cold and likely forming condensation there. Working out how to fix it in place is an interesting challenge. ISTR I used a very thin masonary bit to drill right through the kingspan and into the wall. Then lift the kingspan out again and drill and plug the holes with regular sized bit. Put the kingspan back in place and screw to the wall. Then for the plasterboard, long drywall screws to initially mark the position of the holes on the kingspan surface, and then drill and plug the wall behind, and fix in place using the long drywall screws.
This was fine for something the size of the back of a fireplace, but I'm not sure what kind of result you'd get doing a whole wall this way. I believe you can have kingspan (or equivalent) sheets made with plasterboard on one side, or a paper side for plastering, or something like that, but it's a special order. If you use separate kingspan/plasterboard sheets, you probably want to make sure the edges are staggered, i.e. you don't have a kingspan join immediately behind a plasterboard join.
The problems you will find are purely practical in that you need to find a way to affix both the insulation and the plasterboard. The foil will indeed act as a vapour barrier. It is best to tape the joins also, so the vapour barrier is continuous.
Christian.
You can do, but the wall may then retain moisture that used to evaporate. I would use battens and a 1" cavity, or thick lumps of plaster adhesive, removing the foil and digging a small crater for the dabs to get adhesion.
I wanted to insulate my garage in this way, and it is certainly worth doing - it makes it quite habitable as a workshop and cheap to heat.
I have a single brick wall garage with a pitched roof of trussed wooden structure, so the task was to insulate roof and walls.
For the roof, I fastened the Celotex to the rafters with long drywall screws and large washers and taped the joints. This left an air space behind for ventilation.
For the walls, I did consider your idea, but rejected it for two reasons.
- I did not feel comfortable with the idea of not having some degree of ventilation on the inner face of the wall to allow drying out of any possible penetrating moisture.
- I wanted to be able to fix shelves, brackets cupboards etc. arbitrarily to the walls.
To achieve this, I built framing using 75x50 pressure treated timber Rawlbolted to the floor with a DPC strip to separate it and fitted to the joists at ceiling level.
The back of the framing left about a 20mm gap to the bricks so there is little loss of space. The Celotex was cut to fit inside the frames and taped.
Finally 18mm WBP ply was screwed to the frames and painted white.
This gives me a surface onto which I can fix ordinary cupboards and shelves anywhere I like using either screws directly or cavity fixings for heavier weights. For very heavy weights like a cyclone dust extractor weighing about 100kg, I attached battens to the framing using coach screws and attached the extractor to them.
This is not to say the plasterboard and insulation attached as you have described won't work, but I would be concerned about moisture and you won't have a substantial surface for attachments if that is important for you
.andy
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No it's a stock item at a decent builders merchant. Just used two sheets of 9.5mm PB bonded to 25mm celotex type foam. This came from British Gypsum I think, look for "thermalboard" or similar via google.
The garage will be a fish house, what if i put 2x1 batton on the wall then fixed the sheets directly on to the batton so creating a 25mm gap between the wall and boards tape this then use a hammer fixing (nylon plug with drive screw) to go through the plasterboard and insulation through to the wall then plaster over the board.
You could do that, but definitely make sure you tape the joints with foil tape. You want to keep any humidity inside and not allow it to reach anything cold.
If you make stands for the aquaria, they will need to be floor supported. No chance of using the walls.
.andy
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