So our house has the garage below the ground floor kitchen, which is fine apart from on days like today where it’s bleedy freezing and there’s an artic wind. This means the garage gets really cold (as it has a up-and-over door) but also makes the kitchen floor cold as it is immediately above the garage.

It looks like there’s actually very little between the garage ceiling and the kitchen floor. From the garage the ceiling looks like concrete rafters with a concrete/brick layer, so I’m thinking that adding insulation on the ceiling between the ‘rafters’ should help keep the cold in the garage.

Does this sound sensible? There’s a pipe and a mains cable running between the rafters, but not a lot of plumbing, so it shouldn’t be too inconvenient. Any suggestions for how to cheaply/easily put insulation on the ceiling, instead of under the floor? Plasterboard panels and stuffing the cavity sounds a bit like too much effort to be honest, especially as the fixing points would be concrete.

Celotex insulation board. Get it as thick as you’ve got room for. Cut channels for any cables/pipes.

I’d look at insulating the garage door and also adding sealing around the edges of it.

Fitting a threshold strip+rubber seals around the sides and top made a huge difference – also adding celotex to the back of the door will help a lot without adding much weight.

Something like https://www.celotex.co.uk/products/ga4000 for the ceiling? Any tips on how to attach it in between the ceiling joists?

I’d cut it as a snug fit and let friction hold it in place.

As WWASWAS – get the garage door insulated and try and block any drafts.
Try it first and see how much of a difference it makes, then think about the floor/ceiling for extra effect.

It’s not the just temp, which celotex will help with, but the drafts that are a major problem…. its a pain.

How much do you like expanding foam ? Because you’re gonna need a lot (probably)

Good Luck

Insulation between joists, airtight membrane over OR expanding foam ask the gaps, then finish with either plasterboard or plywood ceiling, taking care to fix membrane in a way that will stop drafts (a batten around edge would work).

I don’t think there are any drafts going from the garage to the rest of the house – the ceiling of the garage is pretty well sealed (no visible gaps at least) and the door from the garage to the rest of the house is a good fit.