Garage Conversion Cost Guide 2026
A garage conversion is one of the most affordable ways to add usable living space to your home. Because the basic structure already exists — walls, roof, and floor slab — you avoid the major costs of foundations and roofing that make extensions expensive.
Whether you're converting a single integral garage into a home office or transforming a double garage into a family room, the main costs are insulation, damp proofing, and finishing to habitable standards. This guide breaks down 2026 pricing by trade to help you evaluate quotes accurately.
Cost summary
| Size | Basic | Standard | Premium |
|---|---|---|---|
| 15m² (single) | £6,000 | £10,725 | £16,620 |
| 20m² (integral) | £8,000 | £14,300 | £22,160 |
| 30m² (double) | £12,000 | £21,450 | £33,240 |
Costs shown are direct trade costs (national average). Apply regional factors below for your area. Main contractor route adds 20–35%.
Trade-by-trade breakdown
Standard specification, mid estimate. Per-sqm rates for direct trades.
Regional cost variations
| Region | Factor | Adjusted cost |
|---|---|---|
| Inner London | ×1.35 | £965/m² |
| Outer London | ×1.22 | £872/m² |
| South East | ×1.08 | £772/m² |
| South West | ×1.00 | £715/m² |
| East Midlands | ×0.92 | £658/m² |
| North West | ×0.90 | £644/m² |
| North East | ×0.85 | £608/m² |
Multiply the national average cost by the regional factor for your area.
Key cost factors
Structural opening complexity
Removing the garage door and forming a new structural opening requires an RSJ or steel lintel. Wider openings or load-bearing walls above increase steelwork costs by £500–£2,000.
Insulation and damp proofing
Garage floors and walls are rarely insulated or damp-proofed. Meeting current Building Regulations for thermal performance requires floor insulation, wall insulation, and a damp proof membrane — adding £2,000–£4,000.
Building Regulations compliance
All garage conversions require Building Regulations approval. The conversion must meet standards for fire safety, structural integrity, ventilation, insulation, and drainage. Budget £300–£700 for Building Control fees.
Planning considerations
Most garage conversions fall under permitted development. However, if your home is in a conservation area, has restrictive covenants, or requires off-street parking, you may need planning permission.
Existing services and utilities
Garages often house boilers, consumer units, or meters. Relocating these services can add £1,000–£3,000 to the project cost.
Frequently asked questions
Do I need planning permission for a garage conversion?
In most cases, no. Garage conversions are usually classed as permitted development because you're not changing the building's external footprint. However, you will need planning permission if your home is listed, in a conservation area, or if the original planning consent included a condition to retain the garage.
How long does a garage conversion take?
A typical single garage conversion takes 3–5 weeks from start to finish. Double garages or conversions that include a WC or utility room may take 5–7 weeks. The work is far less disruptive than an extension.
Is a garage conversion worth it?
Yes — garage conversions typically add 10–15% to your property's value and cost significantly less than an extension. A well-finished conversion creating a usable room consistently delivers a strong return on investment.
Do I need Building Regulations approval?
Yes, always. Even though planning permission is rarely needed, Building Regulations approval is mandatory. The building inspector will check structural integrity, fire safety, insulation, ventilation, and damp proofing.
Can I convert an integral garage?
Yes, integral garages are often easier to convert because they already share walls with the house. The main work involves removing the garage door, infilling the opening, levelling the floor, and insulating to habitable standards.
Will a garage conversion add value to my house?
Most estate agents agree that a well-executed garage conversion adds more value than the cost of the work. The key is quality finishing — a poorly converted garage with visible signs of its former use can actually reduce appeal.
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