DATA-BACKED GUIDE · UPDATED JULY 2026
How to get honest quotes for a garage conversion
The gap between two garage conversion quotes can be huge, and it is not always because one builder is greedy. Often they have simply priced different jobs. One has allowed for a new floor and damp-proofing, the other has assumed the existing slab is fine and skipped it. Here is how to get quotes you can actually compare, then check them against the real prices below.
The quick version
- Ask every builder to price the same written scope so you compare like with like, not just three numbers on a page.
- A garage conversion is building work, so 20% VAT should be shown clearly on the quote, not bolted on later once you have agreed a price.
- Local builders usually come in below national conversion firms for the same job, because they carry less advertising and finance overhead.
- Get three quotes so you can spot the outlier that is either cutting corners or padding the price, and ask why it differs.
- Check what is excluded as closely as what is included. Flooring, decorating and electrics are the most common gaps that reappear as extras.
- A quote with no detail on floor works, insulation or the door opening is not really a quote. It is a guess with a number attached.
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
Quotes vary because builders make different assumptions about what your garage needs, and because the businesses behind the quotes are not all built the same way. A one-person local builder working out of a van has low overheads and prices the job in front of them. A national conversion firm, often set up to sell finance packages alongside the build, has sales staff, marketing and a franchise model to cover, and that shows up in the price before a single brick is touched. Region matters too: what a builder charges reflects local labour rates and how much competing work is around, so the same conversion can cost noticeably different amounts depending on where in the country you are. On top of that, one builder might allow for a full new floor and damp-proof membrane, another might assume the slab is fine. One might include finishing the room ready to decorate, another might stop at bare plaster. The door opening, the insulation spec and whether any plumbing is involved all move the number. Until every quote covers the same list of work, the cheapest one on paper can end up the dearest once the extras land.
How to pay less
- Write a short scope of what you want, room by room if the job is more than one space, and hand the same one to each builder so the quotes line up.
- Get three quotes and lean towards established local trades rather than a national brand that sells finance, since that finance is priced into the job.
- Ask what is excluded, since flooring, decorating and electrics are common gaps that reappear as extras once the main work is done.
- Pay the deposit by credit card for Section 75 cover, and never hand over a big cash sum up front, however keen the discount sounds.
- Push back on any quote that is a single line total. Ask for it broken down by floor, insulation, door infill, electrics and plastering so you can see where the money goes.
- If one quote is well below the other two, ask directly what has been left out rather than assuming it is simply the best price.
Common questions
How many quotes should I get for a garage conversion?
Three is the sweet spot. One quote gives you nothing to judge it against, and two can both be off in the same direction. Three lets you see the middle ground and question anything that sits well above or below it.
Should I use a national garage conversion company?
You can, but national firms usually quote above local builders for the same work, partly to cover advertising and finance deals. If you go that route, still get three quotes from local trades so you know what a fair price looks like before you sign anything.
What should a written garage conversion quote include?
It should list the floor works, insulation, how the door opening is filled, electrics, plastering and any decorating, plus VAT shown separately. A vague one-line price is a red flag. The more detail it holds, the easier it is to hold the builder to it later.
Why is one quote so much cheaper than the others?
Ask what has been left out before you assume it is a bargain. A low quote often skips flooring, damp-proofing or finishing work that the other builders have included, and those gaps tend to come back as extras once the job is under way. Compare the written scope line by line, not just the total.
Is VAT included in a garage conversion quote?
It should be shown as a separate line at 20%, not folded into a round total. If a quote does not mention VAT at all, ask directly whether the builder is VAT registered and whether the figure you have been given is before or after it.
How should I pay a builder for a garage conversion?
Pay the deposit by credit card where you can, since that gives you Section 75 protection if the job goes wrong or the builder does not finish. Avoid handing over a large cash sum before work starts, and agree stage payments tied to completed work rather than one big upfront figure.