On 20 Oct 2004 02:30:33 -0700, (eddie) wrote:

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.


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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