What insulation should I use?

[wv62]

Hi all

I'm starting to do some work on a holiday chalet I inherited near Minehead. The chalet is wood built with approx 3" gap between the outer and inner walls. Currently the gap is filled with a thin (1-2") layer of what looks like roof insulation. I'm looking for suggestions to replace this which will give me better heat and, if possible, sound insulation.

 

[JohnD]

rigid foam slab such as Kingspan or Celotex has about twice the insulating power as the same thickness of mineral wool quilt. However the mineral wool is cheaper.

It is quite difficult to cut the foam to be a perfect tight fit between timbers with no draughts, the quilt stuffs tightly into an irregular gap so is easy to fit between joists or studs.

If you have cladding or plasterboard, you can nail the foam slabs onto the face of the frame to a tight fit.

Remember to do the ceiling and floor.

 

[wv62]

It is quite difficult to cut the foam to be a perfect tight fit between timbers with no draughts, the quilt stuffs tightly into an irregular gap so is easy to fit between joists or studs.

What about using the foam and filling any gaps between the timbers and the sheet foam with the aerosol expanding foam stuff? Can you see any problems with that?

 

[JohnD]

OK as sure as it's away from any possible rain or condensation. Aerosol foam seems to hold water, which will rot the wooden frame.

 

[wv62]

I suppose another possibility is to use the sheet foam and fill any small gaps by squeezing in as much of the quilt stuff as possible? I suppose the problem there would be the same. Wouldn't the quilt soak up and hold any moisture too?

 

[theprinceofdarkness]

Before seaingl the inner skin, make sure that you include a vapour control layer (thin plastic film), else the hot moist air from inside will result in condensation within the insulation and rot in the frames.
Frank