Garage Conversion Cost UK 2026: Prices and Planning
What it costs to turn a garage into a bedroom, office, playroom or utility in 2026, line by line, with the planning catches on newer estates and the building regulations that apply.
Key takeaways
- A basic single garage conversion typically costs £8,000 to £14,000 in 2026; a well-finished room £12,000 to £22,000.
- Adding a shower room or utility takes most projects to £18,000 to £30,000.
- Most integral garage conversions are permitted development, but many newer estates have conditions removing that right.
- Building regulations approval is always needed because the garage becomes a habitable room.
On this page (11 sections)
A garage conversion in the UK typically costs £8,000 to £14,000 for a basic single garage, £12,000 to £22,000 for a well-finished room with heating, and £18,000 to £30,000 if you add a shower room or utility in 2026, excluding VAT. A double garage costs £20,000 to £40,000. Most integral garage conversions are permitted development, but building regulations approval is always needed.
Because the walls, roof and foundations already exist, a garage conversion costs a fraction of an extension per square metre and is usually finished in two to six weeks. This guide breaks down every line of the cost, explains the planning condition that catches out owners on newer estates, and covers the building regulations, timescales and the best uses for the space.
Garage conversion cost at a glance (2026)
| Garage conversion | Typical cost | Typical time on site |
|---|---|---|
| Single integral or attached garage, basic room | £8,000 – £14,000 | 2 – 4 weeks |
| Single garage, finished room with heating and good spec | £12,000 – £22,000 | 3 – 5 weeks |
| Single garage with a shower room or utility | £18,000 – £30,000 | 4 – 6 weeks |
| Double garage | £20,000 – £40,000 | 4 – 8 weeks |
| Detached garage converted to an office or annexe | £18,000 – £35,000+ | 4 – 8 weeks |
Per square metre, a garage conversion typically costs £700 to £2,000, from a basic room at the bottom to one with a shower room at the top, well under the rate for a new extension because the shell already exists. Figures are based on 2026 trade price guides, including Checkatrade's, with a south Hampshire uplift.
Garage conversion cost by scope (2026, ex VAT)
Cost breakdown
The biggest lines are infilling the garage door opening at £2,000 to £4,500 and an optional shower room or utility at £5,000 to £12,000; building control adds £500 to £1,000 on every conversion.
| Item | Typical cost | What is involved |
|---|---|---|
| Infilling the garage door opening | £2,000 – £4,500 | New insulated cavity wall, window, brick to match |
| Foundations under the new wall | £300 – £1,500 | Checked by building control; sometimes needs a new footing |
| Floor | £1,000 – £3,000 | Damp-proof membrane, insulation, screed raised to house level |
| Wall and ceiling insulation | £1,500 – £3,500 | Insulated plasterboard or a stud wall with insulation |
| Electrics | £1,000 – £2,500 | New circuit, sockets, lighting, smoke alarm |
| Heating | £400 – £2,000 | Extending the radiator circuit, or electric underfloor heating |
| Plastering and decoration | £1,000 – £2,500 | |
| Internal door or opening into the house | £300 – £1,500 | More if knocking through a loadbearing wall |
| Flooring | £600 – £1,800 | |
| Shower room or utility (optional) | £5,000 – £12,000 | Depends on the drainage route |
| Building control | £500 – £1,000 | Always needed |
Do you need planning permission?
Converting an integral or attached garage into a room is usually permitted development, because the work is mostly internal and the change to the front is small. But there are three common catches:
- Estates with conditions. Many homes on estates built since the 1980s, the kind found across Hedge End, Whiteley and Chandler's Ford, were approved with a condition removing permitted development rights for garage conversions, usually to protect parking. Not every estate has one, but if yours does, you need a planning application, normally £548 for a householder application. Check the original planning permission for the estate on the council's website or ask us to look.
- Conservation areas and listed buildings. Changes to the front elevation usually need permission.
- Detached garages. Using a detached garage as an office or gym is normally fine, but turning it into self-contained living accommodation, an annexe with a bedroom, kitchen and bathroom, needs planning permission.
Where no application is needed, a Lawful Development Certificate (£274, see the Planning Portal) gives you written proof for a future buyer. If the garage shares a wall with your neighbour's and you plan to cut into or build up that wall, read our guide to party wall agreements first.
Building regulations
A garage conversion always needs building regulations approval, because it turns a non-habitable space into a habitable one. Building control will check:
- Foundations under the new wall where the garage door was
- Damp-proofing of the floor and walls
- Insulation of the floor, walls and ceiling to current standards
- Ventilation, including background ventilation and an extractor fan in any shower room or utility
- Fire safety and escape, including a mains-wired smoke alarm and, where the room is reached through another room, a window large enough to escape through
- Electrics, installed and certified by a registered electrician
You receive a completion certificate at the end. Without it, a buyer's solicitor will raise questions when you sell.
The garage conversion process
- 1
Survey and planning checkWeek 1
Check the structure, floor levels, damp and drainage, and look up the planning history for conditions on garage use.
- 2
Drawings and approvalsWeeks 2 to 8
Building regulations application, plus a Lawful Development Certificate or planning application where needed.
- 3
Door infill and foundationsOn site, week 1
The garage door comes out, a footing is checked or built, and the new insulated wall and window go in.
- 4
Floor, insulation and first fixWeeks 1 to 2
Damp-proof membrane, insulation and screed raised to house level; new circuits, heating and any plumbing.
- 5
Plaster, second fix and finishWeeks 2 to 4
Plastering, sockets and lights, heating, flooring, decoration and the building control sign-off.
How long does it take?
A straightforward single garage conversion usually takes two to four weeks on site. Adding a shower room or utility, or converting a double garage, extends that to four to eight weeks. If you need planning permission, allow eight weeks for the decision before work starts.
Garage conversion vs extension
| Factor | Garage conversion | Single-storey extension |
|---|---|---|
| Typical cost | £8,000 – £22,000 | £60,000 – £130,000 (Southampton) |
| Time on site | 2 – 6 weeks | 12 – 16 weeks |
| Planning | Usually permitted development | Often permitted development, sometimes full planning |
| Space gained | Converts existing space | Adds new footprint |
| Garden | Unaffected | Reduced |
A garage conversion is the better choice when you need one extra room on a budget. An extension is the better choice when you want to change how the ground floor works, such as a larger kitchen-diner opening onto the garden.
Popular uses and what they add
The most popular uses are a home office, a bedroom with a shower room, a playroom, a utility or a gym; only the shower room and the utility need a drainage route.
- Home office: a popular use since 2020; insulation, good lighting and enough sockets matter most.
- Bedroom with shower room: ideal for a teenager, a relative or a downstairs bedroom for later life; needs a drainage route.
- Playroom or snug: keeps clutter out of the main living space.
- Utility room: frees up the kitchen; often combined with a front store.
- Gym: check the floor build-up can take the equipment and the ceiling height suits it.
Common mistakes
- Not checking for a planning condition. Converting without permission where a condition applies can lead to enforcement action and problems when you sell.
- Leaving a step down into the room. Raising the floor to the level of the house is worth the cost; a step makes the room feel like a garage forever.
- Skimping on insulation. A cold, thin wall where the door was is the most common complaint about cheap conversions.
- Forgetting ventilation. A converted room needs background ventilation, and an extractor if it is a shower room or utility.
- Ignoring parking. On streets where spaces are scarce, losing the garage can affect resale.
Questions to ask before you start
- Does the original planning permission for the house restrict converting the garage?
- Is the existing slab sound, and how much will the floor need to be raised?
- Is there a footing under the garage door opening, or will one be needed?
- Where will the drainage go if you want a WC, shower or utility?
- Will the new room be reached through another room, and does that affect the escape window?
Garage conversions in Southampton
Garage conversions around Southampton are mostly on 1990s and 2000s homes with integral garages in places such as Hedge End, Whiteley, Chandler's Ford and Locks Heath, where the garage is too narrow for a modern car and has become a storeroom. Checking for planning conditions is the first job. Our house extension team in Southampton handles garage conversions alongside extensions, so if a conversion is not enough on its own, we can price both.
Get a garage conversion quote
We check the planning history, the structure and the floor levels, and give you a detailed written quote broken down line by line, with VAT stated clearly. Free survey, no obligation.
Written by
The Pure Renovation & Design team
A Southampton design-and-build company whose team has 18 years of hands-on experience in extensions, loft conversions, full renovations, bathrooms and joinery across Hampshire. Prices are cross-checked against published UK trade cost guides and official fee schedules, and reviewed whenever prices or rules change.
Last reviewed 13 October 2026 · About the team
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