Garage conversion costs - double height

[little0miss0mac]

We're contemplating putting an offer in on a house that would only work for us if we do a double height conversion on the double garage.

The garage is joined to the house already, and we'd turn the ground floor into a reception room with a bedroom/en-suite above.

I'm finding it tricky to find ballpark costs online for this just to give us a feel, without actually asking a builder to quote. I wondered if anyone here has had it done and wouldn't mind sharing what it cost them? Clearly there will be a wide margin for variation given finishes, part of the country etc, but any intel/experience as a starting point would be most welcome.

Thanks!

depends on if you need new foundations, where the soil pipe/drains are...what kind of finish. There's on line calculators for extension costs but materials and labour have gone up about 50% where we live.

Thanks. Re plumbing, the new bathroom would be next door to an existing one so I'm (wildly) guessing it could share the pipes, or the plumbing would at least be simpler than if no existing bathroom.

Thanks for the tip about online calculators - I'll have a dig around for those.

A good many years ago our neighbours looked at a demolition of a single garage to build a double-height extension including a kitchen extension next to the current kitchen. In a cheapish area of the UK it came out at 30 thousand, that's not including decor, fittings or the kitchen itself, just the bare building, architects drawings and planning. Add to that a double garage, fittings, and price rises due to covid/brexit and I'd make a guess that you'd see little change back out of 100 grand.
Most garages haven't got foundations fit for upper storeys, hence the demolition, which costs a lot, and new foundations.

We have demolished a single garage plus some small outbuildings and replacing with 2 storey extension plus replacing a conservatory with a single storey brick extension at the back. We are in the NW and it's currently costing £240k to 2nd fix. Costs are increasing daily and the wait times for some materials horrendously long.

Our builder quoted us £50K in June and has upped it to £65K to knock through into single garage and put bedroom above. That's just for the shell. So I'm budgeting £100K

Thanks everyone. Lots to think about, particularly the point about building supply costs rising exponentially.

We really have chosen the wrong time to move: nothing on the market, what there is is overpriced, and costs for building work going through the roof! So depressing.