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 the space up to a habitable standard rather than building anything from scratch. The real prices on this page show what a garage conversion typically runs to, so you can see where the money actually goes before you get a quote.
The quick version
- A garage conversion is usually cheaper than an extension because the main structure already exists and you are upgrading it rather than building new walls, foundations and a roof.
- Most of the cost goes on insulation, a new front wall and window, damp proofing, heating and rewiring, not on the shell itself, which is already standing.
- Many garage conversions fall under permitted development, though this is not guaranteed, especially for a detached garage or a house in a conservation area.
- Building regulations sign-off is required regardless of planning status, and covers insulation, damp proofing, ventilation and fire safety.
- Adding a bathroom or kitchenette is one of the biggest single jumps in price because it brings in plumbing, drainage and often a new consumer unit circuit.
- The condition of the existing garage floor and roof has a big effect on cost, since a sound structure needs far less work than one that has to be dug out or rebuilt.
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 actually needs is the main variable, more than the size of the room you end up with. An integral garage attached to the house is simpler and cheaper to convert than a detached one, which often needs new heating and drainage runs brought over from the main building. The floor level frequently has to be raised and damp proofed, since garage floors are built to a different standard to a living room floor, and the single skin walls common in older garages may need insulating out or rebuilding entirely to meet current regulations. Adding a bathroom or a kitchenette pushes the price up sharply through plumbing, drainage and extra electrical work. The finish you want also sets the top of the range: a plain home office costs far less than a fully fitted annexe with its own kitchen and bathroom. Who does the work matters too. A local independent builder pricing a single job will quote differently to a larger conversion specialist with its own design and building regulations service, and prices also vary by region, with labour and material costs higher in and around London and the South East than in most of the rest of the country.
How to pay less
- Keep the existing floor and roof if they are sound, and put the budget into insulation and damp proofing instead, which you will not see but will feel every day the room is used.
- Convert an integral garage rather than a detached one where you have the choice, since the services (electrics, heating, water) are already close by and do not need long new runs.
- Avoid adding plumbing unless you genuinely need it. A bathroom or kitchenette is one of the biggest single cost jumps, so a plain home office or bedroom will always come in cheaper.
- Reuse the existing garage opening for a window and standard wall rather than reshaping the whole front elevation, which adds cost for brickwork, structural work and finishing.
- Get quotes that separate the structural work from the fit-out, so you can see clearly where a cheaper finish or fewer fittings would bring the total down.
- Ask early whether building regulations sign-off is included in the quote. A conversion that skips this is not legally habitable and will cause problems if you come to sell.
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, or those already extended close to their permitted limit, are more likely to need a formal check. You will always need building regulations sign-off separately, to make the room legally habitable, regardless of the planning position.
Why does a garage conversion still cost a fair amount if the walls and roof are already there?
The shell is already standing, 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 turn a cold storage space into a warm, dry room, and they cost more than most people expect before getting a quote.
Will I lose parking value by converting my garage?
In some areas losing off-street parking can affect resale value, so it is worth weighing that against the extra living space you gain. The real prices on this page help you judge whether the spend and the trade-off make sense for your street and your plans for the house.
Is it cheaper to convert a garage than to build an extension?
Generally yes, because you are not paying for new foundations, walls and a roof, which make up a large share of extension costs. A garage conversion instead spends its budget on insulation, damp proofing and services, so the total is usually lower for a similar-sized room, though a poor-condition garage can close that gap.
Does adding a bathroom or kitchenette to a garage conversion cost a lot more?
Yes, this is one of the biggest single jumps in the price. Plumbing and drainage need to be brought into a space that did not have them, which often means digging up part of the floor, and you may need a new circuit on the consumer unit as well. If budget is tight, leaving plumbing out is the simplest way to keep costs down.
What condition does my existing garage need to be in before converting it?
A sound floor and roof keep the cost down considerably, since they can often be kept and simply upgraded rather than replaced. Single skin walls, common in older garages, usually need insulating out or rebuilding to meet current building regulations, and any damp or structural issues should be sorted before the room is closed up, since they are far harder to fix afterwards.