Garage Conversion London 2025: Complete Guide
Transform your garage into valuable living space. Costs, planning rules, building regulations, and design ideas for London homeowners.
Garage Conversion: Key Facts
- Average cost: £15,000-£25,000 (single), £25,000-£45,000 (double)
- Build time: 4-8 weeks typically
- Planning: Usually permitted development (no permission needed)
- Get instant cost estimate for your conversion (Free)
Garage conversions are one of the most cost-effective ways to add living space to your London home. With land at a premium and many garages used only for storage, converting this space into a bedroom, office, or living area makes financial sense.
A well-executed garage conversion can add 10-15% to your property value while providing an extra room that suits your lifestyle needs.
Garage Conversion Costs in London
| Conversion Type | Size | Cost Range |
|---|---|---|
| Single garage (basic) | ~15m² | £15,000 - £20,000 |
| Single garage (with bathroom) | ~15m² | £22,000 - £30,000 |
| Double garage (basic) | ~30m² | £25,000 - £35,000 |
| Double garage (high spec) | ~30m² | £35,000 - £45,000 |
What's Included in These Costs?
- Replacing garage door with wall and window
- Floor levelling and insulation
- Wall and ceiling insulation
- Electrics and heating
- Plastering and decoration
Do You Need Planning Permission?
Most garage conversions in London do not require planning permission as they fall under permitted development rights. You are simply changing the use of existing space.
When You DO Need Planning Permission
- Listed building: Listed building consent always required
- Conservation area: May need permission for external changes
- Flat/maisonette: Not covered by permitted development
- Creating separate dwelling: Always needs permission
- Parking condition: Check original planning consent for restrictions
Tip: Use our Permitted Development Checker to check if your garage conversion needs planning permission.
Building Regulations Requirements
Even when planning permission is not needed, building regulations approval is always required for garage conversions to ensure safety and energy efficiency.
Thermal Performance (Part L)
Walls, floor, and roof must meet insulation standards. Windows must be double-glazed. This ensures the room is warm and energy efficient.
Fire Safety (Part B)
Fire separation must be maintained between garage and house. Smoke detectors required. Fire doors may be needed if garage was previously attached.
Ventilation (Part F)
Habitable rooms need opening windows for natural ventilation. Bathrooms and WCs need mechanical extract ventilation.
Structural (Part A)
If there is a room above the garage, or if removing walls, structural calculations may be required to ensure stability.
Popular Garage Conversion Ideas
Home Office
Ideal for remote workers. Good natural light essential. Consider sound insulation for video calls.
Cost: £15,000 - £22,000
Extra Bedroom
Popular for growing families. Consider adding an ensuite bathroom for maximum value.
Cost: £18,000 - £28,000
Playroom / Games Room
Keep toys and noise separate from main living areas. Good soundproofing recommended.
Cost: £15,000 - £20,000
Home Gym
Floor must support heavy equipment. Good ventilation essential. Rubber flooring recommended.
Cost: £15,000 - £25,000
The Conversion Process
- 1Design & Planning: Decide on room use and layout. Check PD rights.
- 2Building Regs Application: Submit plans to building control (£300-£500).
- 3Get Quotes: Obtain 3+ quotes from reputable builders.
- 4Construction: 4-8 weeks typically. Work includes door infill, insulation, services.
- 5Sign Off: Building control inspection and completion certificate.
Get a Free Cost Estimate
Use our free calculator to estimate costs for your garage conversion project.
Frequently Asked Questions
Will a garage conversion add value to my home?
Yes, typically 10-15% for a well-executed conversion. However, in some areas losing a garage can reduce value—check local market expectations before proceeding.
How long does a garage conversion take?
4-8 weeks for construction, plus 2-4 weeks for building control approval. Total timeline typically 8-15 weeks from start to finish.
Do I need a structural engineer?
Usually only if there is a room above the garage, or if making significant structural changes such as removing load-bearing walls.
Can I convert an integral garage?
Yes, integral (attached) garages are often easier to convert as they share walls with the house. Fire separation and insulation requirements still apply.