2 November 2023 · Sharon Winson
How much does it cost to turn a double garage into a room?
A simple double garage conversion starts around £5,000 as a guide; a full conversion with plumbing can pass £20,000. Here's the cost of each stage.
As a guide, turning a double garage into a room costs from around £5,000 for a simple conversion — insulation, boarding, basic electrics — up to £20,000 or more for a full conversion with new doors, plumbing and finished flooring. The door, the insulation and the electrics are where most of the money goes.
What does each part of a garage conversion cost?
Every conversion is different, but the same jobs come up every time. The ranges below are guide figures from when this article was written — get current quotes locally before you budget.
| Conversion job | Guide cost |
|---|---|
| Replacing the garage door with a wall, window or patio doors | £1,000–£5,000+ |
| Basic insulation | £1,000–£2,500 |
| Comprehensive insulation (walls, roof and floor) | £2,500–£5,000 |
| Timber framing and plasterboard | £1,500–£3,000 |
| Plaster skimming | £1,000–£2,000 |
| Electrics and lighting | £1,000–£3,000+ |
| Flooring, skirting and painting | £1,000–£5,000 |
| Plumbing for a sink or kitchenette | £2,000–£4,000 |
Why does the garage door cost so much to replace?
The garage door opening is the single biggest change. Bricking it up with a window is the cheaper end; glazed patio or bi-fold doors across a double-width opening sit at the expensive end. This one decision — as a guide, anywhere from £1,000 to £5,000 or more — shapes both the budget and how much the room feels like part of the house.
How much insulation does a converted garage need?
More than most people expect. A garage was built to keep a car dry, not a person warm, so walls, roof and often the floor all need insulating for the room to be usable year-round. Basic insulation keeps costs down; a comprehensive job roughly doubles it but makes the difference between a room you use and one you avoid in January. Framing and plasterboard over the insulation, then a plaster skim, get the walls ready for decoration.
Can you convert just part of a double garage?
Yes — and it's a popular way to keep the cost down. A partial conversion turns half the double garage into a home office or gym while the other half keeps its garage door and stays as parking or storage. You spend less on doors and flooring, keep somewhere for the lawnmower, and retain more flexibility if you sell.
Is converting the garage worth it — and what about the storage you lose?
A well-done conversion adds usable space and can add value — our guide to how much value a double garage adds to a house looks at both sides of that trade. But remember what you're giving up: buyers consistently value garage space, and everything currently stored in yours has to go somewhere. Many of our customers convert their attached garage and put a new concrete double garage in the garden to replace the parking and storage — often for less than the conversion itself costs. Every Nucrete price includes VAT, delivery and installation, and installation typically takes around a day.
How much does a double garage conversion cost in total?
As a guide, from around £5,000 for a simple conversion to £20,000 or more for a full conversion with new glazed doors, comprehensive insulation and plumbing. Costs move, so get local quotes before budgeting.
What's the cheapest way to convert a double garage?
A partial conversion — turn half into a room and keep the other half as a garage. You save on the door replacement and flooring, and you keep your storage.
Do I need professionals for a garage conversion?
For electrics and plumbing, yes — both must be done by qualified trades to meet safety regulations, and a habitable room needs to comply with building regulations.
Where does the garage's contents go after a conversion?
That's the catch most people hit. A detached concrete garage or shed in the garden is the usual answer — it replaces the lost storage and keeps the converted room clutter-free.