Key Takeaways
- A garage conversion in London typically costs £10,000 to £25,000, making it one of the cheapest ways to add a room.
- Most integral garage conversions fall under Permitted Development, but Building Regulations always apply.
- Key works are insulation, damp-proofing, a new floor, infilling the garage door and heating.
- It adds usable space such as a home office, bedroom or playroom at a low cost per square metre.
- Converting loses off-street parking, which can affect value in some London areas.
If you have an integral or attached garage you rarely use for the car, converting it is one of the cheapest ways to add a proper room. Here is what a garage conversion costs in London in 2026, the rules that apply, and whether it adds value.
How much does a garage conversion cost?
A garage conversion in London typically costs £10,000 to £25,000, depending on the size of the garage, the condition of the structure, and whether you add plumbing. Compared with an extension or loft conversion, it is inexpensive per square metre because the walls, roof and foundations already exist.
| Conversion type | Typical London cost |
|---|---|
| Single garage, simple room | £10,000 to £15,000 |
| Single garage with plumbing (office, shower room) | £15,000 to £20,000 |
| Double garage or high-spec | £20,000 to £25,000+ |
What work is involved?
A garage was never built to habitable standards, so the conversion brings it up to spec. Typical works include:
- Insulating the walls, floor and roof to meet Building Regulations
- Damp-proofing and often a new, raised, insulated floor
- Infilling the garage door opening with a wall and window
- Upgrading electrics and adding heating
- Plastering, flooring and decoration
- Plumbing, if the room will be a bathroom, utility or kitchenette
Planning and building regulations
Converting an integral garage usually falls under Permitted Development and does not need planning permission, provided you are not enlarging the building. However, Building Regulations always apply, covering insulation, ventilation, fire safety and structure. Conservation areas and Article 4 directions can remove permitted development rights, so always check first. We confirm the position for your property.
Does it add value, and is it worth it?
A garage conversion turns dead space into a home office, bedroom, playroom or gym at a low cost, which usually adds value. The one caveat in London is parking: where off-street parking is scarce and valuable, losing it can offset the gain. If you rarely use the garage for a car and need the room more, it is one of the best-value projects available. For a free quote, contact us or call 07472 424 226.