Is it worth insulating a garage ceiling below a bedroom?

Avoriaz

Hi, is it worth insulating the ceiling of an integral single garage directly below a bedroom?

We live in a modern 2005 built 4 bed house with an integral single garage about 6 x 2.6 meters. The house is well insulated and easy to warm up and keep warm.

The 4th bedroom is directly over the garage and usually feels substantially cooler than the rest of the house. We haven’t worried about it since we moved in last year, as we don’t use it.

However we are now making it a den/music room/2nd TV room.

It is a longish rectangle, about 5 x 2.6 metres. The long outside wall faces due north. There is a dormer window on the short outside wall facing due west. It therefore doesn’t get much in the way of heat from the sun. The other short wall is to the 3rd bedroom and the other long wall to the main bedroom, landing and stairs.

The picture below shows the garage and the dormer window of the 4th bedroom.

I know heat rises but I think the bedroom must be losing a fair bit of heat into the cold garage below.

I don’t mind spending a few hundred pounds insulating the garage ceiling if it will make a comfort difference. I don’t expect to recover the cost in reduced heating costs.

Might this be worth doing or are we unlikely to notice much difference?

I am considering something like Celotex boards or maybe building a lightweight wooden frame to support rolls of thick loft insulation.

The garage has a metal up and over door. It does have some draught seals but there are still gaps for cold air to get in. We use the garage regularly so there is little point trying to insulate the door.

The garage ceiling is plasterboard or something similar. I don’t know if there is already some insulation above it. Is this standard practice? Could I check by boring a small exploratory hole?

Comments advice and suggestions would be appreciated.

Thanks.

FilthyLuka

there should already be insulation betweent the garage and the room above. This would be to the same standard as the ground floor of the house. i would go with the celotex board to the ceiling if you want to add extra

Gloomendoom

Because there is room above the garage, I believe that you will need to ensure that the fireproofing of the ceiling still meets building regs after you increase the insulation.

julianashcroft

You could cut a small hole in the existing garage ceiling to have a look at what's above in the way of insulation. If you know where the joists are it would be a pretty simple job to screw insulated plasterboard to the ceiling to add a bit of extra insulation.

googler

I had same problem with lounge above garage, with garage door facing prevailing wind.

I realised that much of the problem was with cold air coming up the edges of the ceiling plasterboard where it met the walls. Enquiry on diynot confirmed that these edge gaps should be sealed with intumescent mastic (fire-retardent). I sealed all around the edges and also the butting lines between sheets of plasterboard, and this made quite a difference for me.

jennifernil

We have a lounge above a double garage. We have insulated with 140mm Kingspan between the joists, then our building regs require 2 layers of plasterboard with staggered joints as fire protection.

dodgydl

As already stated, with the house being built in 2005 there should already be insulation there.
You should be able to check either by looking from below (either small hole in the ceiling or cut/remove a small section of plasterboard) or lift a small section of floor above to take a look (whatever is easier).
We have an older house with an internal garage and found there was no insulation between the garage ceiling and the floor above. So we insulated between with 100mm Kingspan and it has made a big difference.
I checked with building regs beforehand and was told to either use 2 layers of plasterboard or 1 layer of fireboard for the ceiling.

And as above, sealing the edges where the wall meets the ceiling makes a difference too

Avoriaz

Thanks for all the replies. Very helpful. :beer:

There is already mastic all around the edges of the ceiling in the garage so there should be no problem with draughts.

We aren't really sure yet how much use the room will get so I think we will just put one of our spare electric heaters in the room and see how we get on over this winter and revisit adding insulation if we find we can't achieve a comfortable level of heat in there without spending a fortune on electricity.

Thanks again for all the posts.

Gastines3

There should beinsulation under the existing,I hope existing,Fire check boarding.If you intend to fix extra insulation, make sure you are covering the garage ceiling with the required fire board and doubling-up the board over any joins.Building regs dprt will advise you.Don't forget cars are a fire source.

thebaldwindowfitter

Have you checked around edges of skirting board for draughts i live in house built in 2000 and draughts come through here ive sealed the gaps to the chip board floor with clear silicon as suggested i would say the floor would be insulated.can you get into the void below the dormer type window very often this can cause draughts due to vents in soffit boards and the walls ie timber and plaster board in your construction could be the cold spot and not garage