Quick Answer
A basic single garage conversion costs £10,000–£20,000 in 2026. A mid-spec conversion with insulation, plastering, electrics and flooring typically runs £15,000–£25,000. A double garage conversion costs £20,000–£40,000 depending on specification and location.
Converting a garage into a liveable room is one of the most cost-effective ways to add space to your home in 2026. Unlike an extension, the structure already exists — you're not paying for foundations or a roof. A garage conversion can create an extra bedroom, home office, gym, playroom or utility room at a fraction of the cost of a full extension. This guide covers everything you need to know: costs, planning rules, Building Regulations and what affects the price.
In this guide
Garage Conversion Costs in 2026
The cost of a garage conversion depends on the size of the garage, the intended use of the new room, and the level of finish. Here are typical price ranges for a standard single garage (approximately 15–20m²) in the UK:
- Basic conversion (insulation, plasterboard, basic electrics, new floor): £10,000–£20,000
- Mid-spec conversion (plastered finish, quality flooring, heating, double glazing): £15,000–£25,000
- High-spec conversion (en-suite, underfloor heating, premium finishes): £20,000–£35,000
- Double garage conversion: £20,000–£40,000
Costs are higher in London and the South East — typically 20–30% above the national average. Adding an en-suite bathroom adds around £3,000–£6,000 to the project cost.
Garage Conversion Cost Breakdown
| Work Element | Typical Cost | Notes |
|---|---|---|
| Structural works / door infill | £1,000–£3,000 | Bricking up garage door opening |
| Insulation (floor, walls, roof) | £1,500–£3,500 | Critical for Building Regs compliance |
| Plastering | £800–£2,000 | Depending on finish standard |
| Electrics (first & second fix) | £800–£2,000 | Sockets, lighting, consumer unit work |
| Flooring (screed + finish) | £600–£2,000 | Screed level; tiles or carpet on top |
| Windows (if new/replacing) | £500–£1,500 | Double glazed units |
| Heating (radiator or UFH) | £500–£2,500 | Extension to existing system |
| En-suite bathroom (optional) | £3,000–£6,000 | Plumbing, sanitaryware, tiling |
| Building Regulations application | £200–£500 | Local authority or Approved Inspector |
| Architect / designer fees | £500–£1,500 | If drawings needed |
| Total (basic single garage) | £10,000–£20,000 | Without bathroom |
| Total (mid-spec single garage) | £15,000–£25,000 | With en-suite: add £3,000–£6,000 |
What a Garage Conversion Involves
A garage conversion typically involves the following works:
- Infilling the garage door opening: The existing door is removed and the opening is bricked or blocked up, usually with a new window and/or door.
- Floor: Garage floors are typically uninsulated concrete slabs. A new insulated floating floor or insulated screed is needed to meet Building Regs thermal requirements.
- Walls: Cavity or solid walls are insulated and lined with plasterboard and skim coat.
- Roof/ceiling: If the garage has a pitched roof, insulation is fitted between or above the rafters. A flat garage roof may need upgrading.
- Electrics: New circuits for sockets and lighting are installed. The consumer unit may need upgrading.
- Heating: A new radiator is run off the existing central heating, or underfloor heating is installed.
- Plumbing (if en-suite): Drainage may need to be routed from the garage to the main stack — this can add significant cost depending on distance.
Planning Rules for Garage Conversions (Usually Permitted Development)
In most cases, converting an attached or detached garage into living space is considered "change of use within a dwellinghouse" and does not require planning permission — it falls under Permitted Development rights. The key is that you're not creating a separate dwelling and you're not making significant external alterations that would themselves require permission.
However, you may need planning permission if:
- The property is in a conservation area or listed
- The original planning consent for your home included a condition requiring a garage to remain as a garage
- You want to add external alterations (like an external door or large window on the front elevation) that exceed PD limits
- Your house has had PD rights removed via an Article 4 Direction
Always check the planning conditions for your property — particularly on estates built since 2000. For more detail, see our guide on planning permission for home extensions and conversions.
Building Regulations for Garage Conversions
Unlike planning permission, Building Regulations approval is always required for a garage conversion. This is non-negotiable and is separate from planning. Building Regs ensure the conversion is safe, structurally sound, thermally efficient and properly connected to services.
Key requirements include:
- Insulation: Floor, walls and roof/ceiling must meet current U-value standards (typically U=0.18 for floors, U=0.13 for external walls)
- Damp proof course: The floor must have a DPC tied into the existing house DPC
- Fire safety: If the garage connects to the house, fire-resistant construction and a fire door may be required
- Structural assessment: The building inspector will assess whether the existing structure can support the conversion
- Ventilation: Adequate ventilation must be provided (particularly for bathrooms if added)
See our Building Regulations guide for full details on the application process and fees.
Does a Garage Conversion Add Value to Your Home?
Generally, yes — though the extent depends on your property and local market. A garage conversion that adds a bedroom or usable living space can add 5–15% to property value. In urban areas where off-street parking is less critical, the value uplift from the extra room often outweighs the loss of the garage.
However, in areas where parking is important (rural locations, larger properties), losing garage space can reduce appeal to some buyers. Speak to a local estate agent before committing — they can give you an honest view of whether your local market values parking or living space more.
When you're ready to find a contractor, our guide on how to hire a builder in the UK will help you get the best quotes and avoid pitfalls.
Frequently Asked Questions
How long does a garage conversion take?+
A straightforward single garage conversion takes around 2–4 weeks for the main building work. Add time for Building Regulations approval (if using Full Plans route) and any additional trades (electrics, plumbing). The whole project from start to finish is typically 6–12 weeks.
Can I convert a detached garage into a separate dwelling?+
Not under Permitted Development — creating a separate self-contained dwelling (with its own front door, kitchen and sleeping accommodation) requires planning permission. It also typically requires a change of use application. This is different from simply converting an attached or detached garage into a room within the main house.
Do I need to tell my mortgage lender about a garage conversion?+
Yes, you should inform your mortgage lender. Most lenders require you to notify them of any structural changes to the property. A garage conversion is unlikely to cause problems, but your lender needs to be aware. Your home insurance should also be updated to reflect the change in use.
Is a garage conversion cheaper than an extension?+
Yes, significantly. Because the structure already exists, you save the cost of foundations, external walls and a new roof. A garage conversion typically costs 40–60% less than a same-size extension. The trade-off is that you lose parking and storage space.
Can I build over a garage that is attached to my neighbour's property?+
If your garage shares a wall with a neighbour, the Party Wall Act 1996 may apply to any works that affect that wall. You may need to serve a Party Wall Notice. See our Party Wall Agreement guide for details.
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