Garage Conversion Costs and Planning Permission UK
A garage conversion typically adds 10-15% to your home value and gives you a whole new room. Here's what's involved.
Why convert a garage?
Most UK garages are too small for modern cars and end up as overflow storage. Converting yours into a proper room — home office, gym, playroom, extra bedroom or self-contained annexe — is one of the cheapest ways to add usable floor area to your house. No extension foundations, no roof work; the structure is already there.
How much does a garage conversion cost?
For a single integral garage (~15m²) fully converted to a habitable room:
- Basic conversion (insulation, dry lining, flooring, basic electrics): £8,000-£12,000 - Mid-range (above + new windows, full lighting plan, radiator, finished plastering): £12,000-£17,000 - Premium (above + en-suite shower room or proper kitchenette for annexe use): £18,000-£28,000
Double garages roughly double the cost as you have more square metres to insulate and fit.
Do you need planning permission?
For most internal garage conversions where you're not changing the external appearance — no. It falls under permitted development. You do need Building Regulations approval (insulation, fire safety, ventilation, structural) but that's normal and we handle it.
You will need planning permission if: you're changing the external look (e.g., bricking up the garage door and adding a window), it's a listed building, you're in a conservation area, or your home has had its permitted development rights removed by a previous owner.
What's involved in the work?
Typical scope: damp-proof membrane on floor and walls, full insulation (floor, walls, ceiling) to current Building Reg U-values, dry lining, plastering, full electrical first/second fix, plumbing if needed, new flooring, internal doors, finished decoration, and bricking up the old garage door with a matching window or wall finish.
How long does it take?
A standard single-garage conversion takes 4-6 weeks start to finish. Annexes with bathroom and kitchenette closer to 8-10 weeks.
Frequently asked.
Will I lose value if I lose my garage?
Generally no — for most UK homes, a habitable room adds more value than the garage was worth. The exception is detached executive homes where the garage is a feature. We'll give you an honest view at the quote stage.
Can you keep part of the garage for storage?
Yes — we often build a partition wall to keep the front third as a storage bay with the original door, and convert the back two-thirds into the new room. Best of both worlds.
Got a project in mind?
Whatever the task — just ask. Free quote, no obligation.
07516 658358