Garage door & wall
Replacing the garage door with an insulated wall, window and door can account for 15-20% of the project cost.
The most common UK garage conversion, turning your existing single garage into a warm, usable room instead of building something new. Read our full cost guide and use the calculator to see what your project would cost.
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Typical all-in prices including labour, materials, insulation, plastering and VAT. Prices vary with garage condition, specification and region.
| Item | Typical Cost | % of Total |
|---|---|---|
| Garage door removal & wall/window | £1,600 | 20% |
| Insulation | £1,900 | 24% |
| Floor slab upgrade | £1,000 | 12% |
| Electrics | £1,100 | 14% |
| Flooring | £1,100 | 14% |
| Plastering | £700 | 9% |
| Decoration | £600 | 7% |
| Subtotal | £7,700 | 100% |
These figures cover the main trade and material costs for a 15m² single garage conversion. They exclude building control fees of around £300–£1,000, damp-proofing of £1,000-£3,000 if the slab needs it, and contractor markup or contingency. This is why the full project cost on this page is £10,000–£18,000.
Replacing the garage door with an insulated wall, window and door can account for 15-20% of the project cost.
A low slab or missing damp-proof membrane may mean extra work to raise and damp-proof the floor.
Walls, floor and ceiling need suitable insulation to meet current habitable-room standards.
Power and heating can often connect to the house, making this cheaper than a detached garage.
A bedroom needs basic services. Adding a WC or shower means extra drainage and plumbing costs.
Simple finishes keep costs down. Premium flooring, storage and bi-fold doors increase the final price.
A single garage conversion is one of the cheapest ways to create an extra room without having the need to extend your home. The main structure is already there so you are simply converting an existing space instead of building the space from the ground up. That is why it costs much less than a house extension project.
The final price of conversion depends on what you want the room to be, the condition of the garage and where you live in the UK. A simple home office or hobby room can cost less than £12,000, while a bedroom with an en suite can cost you £24,000 or more.
A standard single garage conversion in the UK costs between the range of £8,000 to £24,000 and the average cost for most homeowners will be around £10,000 to £18,000 for a simple home office or bedroom. Most single garages measure between 13 to 18 m² (around 6m × 3m) and the cost for conversion ranges from £900 to £1,800 per m².
If you choose a basic conversion with things including insulation, plastering, flooring and standard electrics, the price will be at the lower end of this range but if you choose to add things like a bathroom, underfloor heating or choose higher-spec finishes then the cost will increase for this job.
You can use our garage conversion cost calculator to get an instant estimate based on the size of your garage and the type of finishing you want for the conversion room.
Following are the three things that have the biggest impact on the cost of a single garage conversion.
Garage type
It is much cheaper to convert a single garage as these types are mainly integral or attached to the house so the main structure and services are already there. A detached single garage can cost you around £4,000 to £8,000 extra because it needs new utility connections and additional building work.
Condition
If your garage is dry and in a good condition then it will cost less to convert because you don't have to fix issues like with dampness or cracked floors. These sort of issues only get visible after the work has started so make sure to get a survey done right before the conversion work starts.
How you'll use the room
The usage of the room that you intent to create has a big effect on the budget. If you want to use it as a home office or hobby room, it would be cost less because no plumbing is required. But if you want it to use as a room with an en suite then the costs could increase by £8,000 to £12,000 because of the plumbing, drainage and ventilation requirements.
Labour
Labour is about 60 to 70% of the total cost. A garage conversion involves a lot of trades, such as builders, electricians, plasterers and decorators and they all work at different stages of the project.
Structural work
Structural work is a major part of the total budget. This means taking off the garage door, putting up a new front wall and doing any structural work required to make the garage a proper room.
| Item | Cost |
|---|---|
| Garage door removal and wall infill | £1,300 – £1,800 |
| New window and/or door installation | £1,200 – £1,800 |
| Floor slab upgrade | £1,000 – £1,500 |
| New stud wall (if needed) | £750 – £1,000 |
| Structural engineer (if required) | £500 – £1,200 |
Insulation and damp-proofing
The whole structure including walls, floor and roof needs to meet the current building regulations. If you garage is already in a good condition, you will have to pay in the range of £1,500 to £3,500 for these add-ons but if damp issues need fixing first, the cost will be higher.
Electrics and plumbing
Putting in lights, sockets and a couple of extra electrical points doesn't add a great deal to the cost. Plumbing costs more. If you choose to add an en suite, the extra costs can be around £2,500 to £5,000 and fully fitted bathroom with drainage system can add £5,500 to £9,000.
Building regulations and professional fees
| Item | Cost |
|---|---|
| Building control application | £300 – £1,000 |
| Architectural drawings (if needed) | £500 – £2,000 |
| Lawful Development Certificate (optional) | £124 – £310 |
Quotes and VAT
Most builders will include VAT in their quotes but it's important to verify before you compare prices. Local builders are normally cheaper than the larger garage conversion companies but larger companies can offer a more comprehensive project management service.
What you turn a single garage into has the biggest effect on the final bill.
| Room type | Cost range |
|---|---|
| Home office / hobby room | £8,000 – £12,000 |
| Bedroom (no en suite) | £10,000 – £16,000 |
| Bedroom with en suite | £16,000 – £24,000 |
A home office is one of the cheapest single garage conversions because there's no plumbing to install. A bedroom costs a little more, mainly because of the extra finishing work. An en suite pushes the price up much further, as it needs plumbing, drainage, ventilation and waterproofing.
| Region | Typical variation |
|---|---|
| London & South East | 15–25% above national average |
| Midlands & East of England | Close to national average |
| North England | 10–15% below national average |
| Scotland & Wales | 5–20% below national average, varies by area |
A single garage conversion costing £14,000 in one part of the UK could cost £16,100 to £17,500 in London or the South East. In parts of the North, Scotland and Wales, the same project could cost less.
Planning permission
Single garage conversions don't need planning permission because the work is carried out inside the existing building. In many cases, the conversion actually falls under Permitted Development.
You may need planning permission if:
Before you start the work, you should check with your local council regarding original planning conditions for your property. You should also try to get a Lawful Development Certificate (£124 to £310) so you have a written proof that the conversion work was lawful.
Building regulations
Building regulations approval is required for almost every single garage conversion because you're creating a habitable room. The work must meet standards covering the structure, insulation, ventilation, fire safety and electrical installation.
Your builder will often deal with the application, but as the homeowner you're responsible for making sure the work complies with the regulations. Building control fees are normally £300 to £1,000, with inspections carried out during the project.
A few extra costs often get overlooked when budgeting for a single garage conversion.
Pre-conversion survey (£360 to £720). A survey can uncover issues like damp, roof or floor problems before the actual work begins and this can help you to avoid expensive surprises later.
Contingency. Keep aside 10 to 15% of your budget for unexpected work. On a £14,000 conversion, that's £1,400 to £2,100.
Garage door removal. This is often included in the quote, but it's worth checking before work starts.
Lawful Development Certificate (£124 to £310). It's optional, but many homeowners choose to get one as proof the conversion was carried out lawfully.
Insurance and mortgage. Let your insurance company know once the garage has been converted. If you have a mortgage, check whether your lender also needs to be informed.
Changes during the build. If the plans need changing to meet building regulations, the work can take longer and cost more.
Measure your garage. Record the internal floor area in square metres by measuring the length and width.
Decide how you'll use the space. Whether it's a home office, bedroom or bedroom with an en suite will have the biggest impact on the final cost.
Get at least three itemised quotes. Choose builders with experience converting single garages and ask for a quote that has a breakdown covering all things including structural work, insulation, electrics, plumbing, building regulations and finishes.
Check what's included. Confirm that building control fees, waste removal and garage door removal are included in the quote.
Check whether permitted development applies. This is especially important if your home is on a newer housing development.
Or, use the calculator below to get an instant estimate based on the size of your garage and the finish you want, then compare quotes from vetted local contractors.
Single garage conversion vs house extension
A garage conversion is much cheaper than a house extension as the walls, roof and base already exist. You are not building new structure and just updating an existing structure and it's one of the most economical ways to add additional living space.
Does it add value?
Converting a single garage is a good way to add value to your home especially if you create an additional bedroom. Parking is the biggest thing to take into account because if you don't have off-street parking after you convert the garage, that may make the property less attractive to some buyers.
How to keep costs down
Everything UK homeowners ask us about single garage conversion costs, planning and building work.
Converting a garage into a bedroom (no en suite) will cost you between £10,000-£16,000. An en suite will push the price up to between £16,000 and £24,000, largely due to the plumbing, drainage and ventilation needed.
The cheapest conversion is a home office or hobby room, ranging from £8,000 to £12,000 as no plumbing is required and only simple electrics. It also keeps costs down by keeping the finish simple and by not changing the structure other than the infill of the door.
Most quotes you get from contractors for a single garage conversion will include 20% VAT but this may not always be the case. Always check with your builder if a quote is inclusive of VAT before comparing prices from contractors.
Single garage conversions will usually cost between £900 - £1,800 per square metre, based on the specifications you go for. The usual size of a single garage is about 13 to 18m². The total cost for most projects is around £10,000 to £18,000.
Yeah, very much. Converting a single garage costs around £900 to £1,800 per square metre against between £1,800 and £3,000 or more for a house extension because the walls, roof and slab are already there.
An integral single garage is less expensive to convert as the walls, roof and services are already connected to the house. The cost of a standard conversion usually increases by between £4,000 and £8,000 for a detached single garage, mainly to provide new utility connections.
In addition to the headline quote, you should budget for a pre-conversion survey (£360 to £720), a 10 to 15% contingency for unforeseen work and a Lawful Development Certificate (£124 to £310) for those who want written evidence that the conversion was lawful.
A building control application for a single garage conversion will cost you between £300 and £1,000 depending on your local authority and whether you opt for a Building Notice or Full Plans application.