Complete guide to garage conversion costs, planning rules, building regulations and how much value it can add to your home.
* Estimates are indicative. Obtain 3 quotes from local builders for accurate pricing. Building regulations application fee (~£200–£400) not included.
| Work Element | Typical Cost | Notes |
|---|---|---|
| Insulation (walls, floor, ceiling) | £1,500 – £3,500 | Must meet Part L building regs |
| Plasterboard & plastering | £1,200 – £2,500 | Including dot & dab or studwork |
| Electrics (re-wire/new circuit) | £800 – £2,000 | Part P certified electrician required |
| Flooring | £500 – £2,500 | Laminate to engineered oak |
| Window installation | £400 – £1,200 | Double-glazed UPVC or timber |
| Garage door removal & infill | £800 – £2,000 | May need structural lintel |
| Heating (radiator/UFH) | £500 – £2,500 | UFH adds significant cost |
| En-suite (if applicable) | £3,000 – £8,000 | Plumbing, tiling, fixtures |
| Decoration | £500 – £1,500 | Often DIY to save cost |
| Building regs application | £200 – £400 | Local authority fee |
| Structural engineer (if needed) | £300 – £700 | For opening modifications |
In most cases, converting an integral or attached garage into habitable space in England does not require planning permission under permitted development rights. This applies when:
Converting a detached garage to a habitable room (such as a bedroom or annexe) typically does require planning permission, as it changes the use of the building. Always check with your local planning authority before starting work.
Regardless of whether planning permission is needed, building regulations approval is always required for a garage conversion. The key parts of the building regulations that apply include:
You must submit a building regulations application to your local council building control department or an approved inspector before work begins. Your builder should handle this as part of the project. The application fee is typically £200–£400 for a single garage conversion.
A properly executed garage conversion is one of the most cost-effective home improvements available in the UK. Research consistently shows that well-converted garages add 5–10% to property value. On a £300,000 home, that represents £15,000–£30,000 of added value.
Converting a garage to a self-contained annexe or studio flat can generate meaningful rental income. A well-converted single garage annexe in the Midlands might achieve £600–£800/month. In the South East, £800–£1,200/month. This can deliver payback on the conversion cost within 2–3 years.
Note that renting out an annexe on your property may affect your council tax banding and potentially create additional tax obligations. Seek advice from a tax professional.
In areas where off-street parking is at a premium, losing a garage for additional living space may make the property less attractive to some buyers. This is particularly true in dense urban areas where parking is limited. In rural or suburban areas with ample parking, this concern is minimal.
Always get at least three written quotes, check references and previous work, and verify the following:
For most integral and attached garage conversions in England, planning permission is not required under permitted development rights. However, you will always need building regulations approval. Exceptions include detached garages being converted to habitable space, properties in conservation areas, listed buildings, and some new-build estates where permitted development rights have been removed by a planning condition. Always check with your Local Planning Authority if you are unsure.
A basic garage conversion in the UK costs £10,000–£20,000 for a standard single garage converted to a habitable room. This includes insulation, plasterboard, basic electrics, a window or door, and flooring. Adding an en-suite bathroom pushes costs to £15,000–£25,000. A fully fitted living space with high-spec finishes can cost £20,000–£35,000. Prices in London and the South East run 15–30% higher.
Yes. A well-executed garage conversion typically adds 5–10% to property value. On a £300,000 home that is £15,000–£30,000 added value against a conversion cost of £10,000–£25,000 — an excellent return. Converting to an additional bedroom (particularly if it increases the bedroom count) tends to deliver the highest value uplift. In areas where parking is scarce, losing a garage space may slightly reduce appeal to some buyers.
Building regulations always apply to garage conversions. Key parts include Part A (structure), Part B (fire safety including fire door between garage and house), Part C (damp proofing), Part F (ventilation), Part L (thermal insulation — walls, floor and ceiling must meet current U-values), and Part P (electrical safety). Your builder must submit an application to your local council building control or an approved inspector before work starts. Always obtain the final completion certificate at the end.
A standard single garage conversion typically takes 4–8 weeks from start to completion. This includes groundworks/DPC, insulation, framing, plasterboard, plastering, electrics, and decoration. More complex conversions with en-suites or major structural changes can take 8–12 weeks. Building regulations final sign-off (and the completion certificate) can take a further 2–4 weeks after the work is finished.
The most popular and valuable uses include: home office (very high demand post-pandemic), additional bedroom (adds significant value especially if it increases the number of bedrooms), self-contained annexe (rental income potential), playroom, or home gym. A bedroom with en-suite or a home office delivers the best return on investment in most markets.
A structural engineer may be needed if the work involves removing or altering the garage door opening (creating a window and solid wall where the door was), modifying load-bearing elements, or changing the roof structure. Building control will advise on this during the application process. Structural engineer fees for a standard garage conversion calculation are typically £300–£700. Always use an engineer registered with the IStructE or ICE.