DATA-BACKED GUIDE · UPDATED JULY 2026
Garage conversion cost UK: turning a garage into a usable room
Converting a garage is one of the cheaper ways to gain a room because the walls, floor and roof are already there. The work is mostly about insulation, a new front wall where the door was, and bringing it up to a habitable standard. The real prices below come from actual prices, so you can see what a garage conversion typically runs to.
The quick version
- A garage conversion is usually cheaper than an extension because the main structure already exists and you are upgrading rather than building from scratch.
- Most of the cost goes on insulation, a new front wall and window, damp proofing, heating and rewiring, not the shell.
- Many garage conversions fall under permitted development, though you should check, especially if the garage is detached.
- Building regulations sign-off is required to make the space legally habitable, covering insulation, damp and ventilation.
What people actually paid
Real prices, in people's own words
- £3,000“Ours was about £3k. We had to pay separately to have a new roof”
- £6,000“We have just had one done and it cost 6k.”
- £9,000“Mine was 9K. Internal garage, large for a single garage.”
- £10,000“Ours was around the 10k Mark”
- £10,000“We paid around £10,000 for the project. That included flooring too.”
- £15,000“We've just spent 15k on a double garage conversion in south wales”
Genuine amounts posted publicly. We publish the price and the quote, never the person.
Why the price varies so much
How much work the garage needs is the main variable. An integral garage attached to the house is simpler and cheaper than a detached one that needs new heating and drainage runs brought over. The floor level often has to be raised and damp proofed, and the single skin walls of older garages may need insulating out or rebuilding. Adding a bathroom or a kitchenette pushes the price up through plumbing. The finish you want, from a plain home office to a fully fitted annexe, sets the top of the range.
How to pay less
- Keep the existing floor and roof if they are sound, and spend the budget on insulation and damp proofing that you cannot see but will feel.
- Convert an integral garage rather than a detached one where you can, since the services are already close by.
- Avoid adding plumbing unless you really need it, as a bathroom or kitchenette is one of the biggest single cost jumps.
- Reuse the existing garage opening for a window and standard wall rather than reshaping the whole front elevation.
Common questions
Do I need planning permission to convert a garage?
Many garage conversions fall under permitted development, so full planning permission is often not needed. Detached garages and homes in conservation areas are more likely to need a check. You will always need building regulations sign-off to make the room legally habitable.
Why does a garage conversion still cost a fair amount?
The shell is already there, but garages are not built to live in. The money goes on insulating the walls, floor and roof, damp proofing, a new front wall and window, heating and rewiring. Those hidden upgrades are what make the space warm and dry.
Will I lose parking value?
In some areas losing off-street parking can affect resale, so weigh that against the extra room. The prices below help you judge whether the spend and the trade-off make sense for your street.