DATA-BACKED GUIDE · UPDATED JULY 2026
What drives the cost of a garage conversion
A garage conversion is one of the cheaper ways to add a proper room, but the final bill swings a lot depending on what the space needs first. Before you look at the real prices below, it helps to know which jobs quietly push the total up.
The quick version
- Most of the cost sits in insulation, damp-proofing and a new floor, not the finishes you actually see.
- An integral garage is usually cheaper to convert than a detached one because the services are close by.
- A garage conversion counts as building work, so expect 20% VAT on most of the labour and materials.
- The real prices below come from actual prices, so you can see what people paid rather than a guess.
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
No two garages start from the same place. A single skin wall needs lining and insulating to meet building regs, while a newer garage built in blockwork may need far less. The floor is another swing factor, since many garages sit lower than the house and need building up and damp-proofing. Then there is what you want the room to do, because a bedroom or office is far simpler than a kitchen or bathroom that needs plumbing and drainage run in. Whether you keep or lose the up-and-over door, and how you fill the opening, changes both the look and the cost.
How to pay less
- Keep plumbing out of it where you can, since a dry room like an office or bedroom avoids the priciest work.
- Get three quotes from local builders and compare what each one includes for the floor and insulation, not just the headline figure.
- Reuse the existing opening rather than widening it, as structural changes mean beams and extra labour.
- If you pay a deposit, put it on a credit card so you get Section 75 protection if the firm folds.
Common questions
Do I need planning permission for a garage conversion?
Usually not, as long as the work stays within the existing walls and you are not on a flat or in a conservation area. It almost always needs building regulations approval though, which covers insulation, fire safety and damp. Check with your council before you start.
Does a garage conversion add value?
It can, especially when it turns a rarely used garage into a bedroom, office or family room. The gain depends on your area and whether buyers there still want off-street parking. In most streets a warm, usable room beats a cold store.
Why is my garage conversion quote so much higher than a friend's?
Starting condition is the usual reason. If your garage needs a new floor, extra damp-proofing or the wall built up to take insulation, that lands before any finishing. Compare the real prices below to see the spread.