Garage ceiling insulation

Hey all,

My house sits on top of its garage and I feel much heat is being lost from the 'ground floor' into the garage. Now, I've never taken apart any of the ground floor, but I suspect beneath the wooden floorboards is some existing, original insulation. Then between that and the garage is just concrete slabs, which are visible if you are inside the garage. No sight of wooden joists, plasterboard or anything like that.

Would insulating the ceiling of the garage make any difference in this case? At first I thought it was fine, but then I don't know if that layer of concrete means any insulation beneath it is rendered useless as far as the living room above is concerned.

Other info: house was built in 1989, cavity wall insulation and with at least 100mm loft insulation as far as I know. (Yes I considered adding another 200m loft insulation...but I'm not sure which option would make a greater difference with respect to the temperature of the ground floor. Heard that up to 25% heat can be lost through the ground...and I can certainly feel it...)

loko

Almost any insulation is good insulation in my view and fixing Kingspan or Celotex boards to the underside of the garage ceiling would certainly help. Tape any joints with foil tape and also seal the perimeter with silicone and you will keep the heat in and the cold out.

Would insulating the ceiling of the garage make any difference in this case?

Click to expand...

If currently not insulated, a very big difference. Having cold feet makes you feel generally uncomfortable.

I recommend fibre-wool as a much more cost-effective solution.

OK, so it sounds like I should embark on this. The next question is then, what kind of options do I have when it comes to actually fixing things (boards/wool) to the ceiling? Its not a flat ceiling; if you imagine a room sized layer of concrete with concrete joists running across the underside, thats how it look from the garage. There are also some water pipes and at the top of the side walls are some plasterboard casings encapsulating something. See image attached.

And DAZB is there any particular 'model' of Kingspan/Celotex you recommend? Will any kind do? Or will it have to include some fire protection/vapour control layer? These are things I have read about recently but am not sure of (along with the terms 'void', 'false ceiling', 'battens', 'noggins'...).

The concrete beams makes it more difficult. I don't know how you would fit wool and as for Celotex etc, can only suggest either wedging them in or holding in place and using expanding foam along the edges. If you do this, don' t do it when it's very cold or the foam won't expand. Also wet the edges of the boards and the beams where the foam will go - aids adhesion.

No vapour-barrier needed, uncertain about fire-control but think very likely not needed> Don't know about any particular type of Celotex, but since it is solely the insulation that interests you, I would go for the cheapest as I believe the insulation properties will always be the same.

Got some cheap polystyrene boards now. Getting them to stick to the slabs and between is a pain though - anyone had experience with good adhesives for this?

Problem is, the PS sheets are very smooth, and non-absorbent obviously, but the concrete slabs aren't smooth - they're the type which have "cracks"/wrinkles in them, which means the surface area between the sheet and the slab is actually relatively small (like 30% or less of the ideal case where both surfaces are 100% smooth & flat).

Want to exhaust the adhesive route before going for expanding foam.

drywall adhesive will stick anything to anything, forever