Garage Conversion Cost in London (2026): Price, Planning & Value

How much does a garage conversion cost in London in 2026?

A garage conversion is one of the cheapest ways to add habitable space to a London home, because the shell — walls, roof, floor slab — is already there. The cost depends on specification: what you're converting it into, and how much of the existing structure needs upgrading.

Indicative 2026 London figures, exclusive of VAT and professional fees. National averages typically run 15–25% lower.

For a standard single garage (15–18 m²), that puts a dry-room conversion at roughly £13,500–£32,000, and a wet-room conversion (bedroom with en-suite, or a utility/kitchenette) at £27,000–£54,000+ once plumbing, a bathroom suite and finishes are added. Double garages (28–34 m²) roughly double the shell cost.

Where does the money actually go?

Unlike a new-build extension, you're not paying for foundations or a roof structure — they exist already. The budget goes on bringing the existing shell up to habitable standard:

• Floor — the garage slab almost always sits below internal floor level and has no damp-proof membrane. A new insulated floor build-up with a DPM is one of the biggest single line items, and the one most often skipped by cheaper quotes.
• Walls — garage walls are typically single-skin blockwork with no cavity insulation. Dot-and-dab insulated plasterboard or a new stud wall lining is needed to meet current thermal standards.
• Roof — check whether the existing roof has any insulation at all; most garage roofs don't. Insulating between or over the rafters (or above the ceiling) is required.
• The door opening — bricking up the garage door and fitting a matching wall and window (or a full glazed unit) usually needs a structural lintel calculation if any load bears on the opening.
• Fire separation — if any part of the garage remains in use for storage or the space is attached to the house, a fire door and 30-minute fire-resisting separation from the rest of the home is required.

Do I need planning permission for a garage conversion in London?

Usually not. Converting an existing garage into habitable space — with no increase in footprint, no change to the roofline, and only minor external changes such as replacing the door with a wall and window — is generally treated as permitted development, and in many cases doesn't count as "development" requiring permission at all. You'll still need Building Regulations approval, which is a separate process and is not optional.

That said, check these before you commit:

• Conservation areas and Article 4 directions. Councils can remove permitted development rights for garage conversions specifically — common where the street scene (including garage doors) is protected, or where a borough wants to preserve off-street parking. Several outer and suburban London boroughs use Article 4 directions for exactly this reason.
• Off-street parking and Controlled Parking Zones. If the garage is your only off-street parking space, some local planning authorities will want it retained, particularly in a CPZ or on a road with known parking stress. This is judged locally — always check with your borough before assuming PD applies.
• Listed buildings. Listed building consent may be required even for internal works, on top of any Building Regs process.
• Detached garages converted into separate self-contained accommodation (with their own kitchen and bathroom, used independently of the house) are a different exercise entirely and are more likely to need a full planning application.

Where PD applies, it's worth applying for a Lawful Development Certificate to put the position beyond doubt before work starts — lenders and buyers will ask for it later if you don't. See our London planning permission guide or use our planning application service to check your specific property.

What Building Regulations apply to a garage conversion?

Building Regulations approval is required for essentially every garage conversion, planning permission or not. The areas building control will check:

• Thermal performance (Part L) — floor, wall and roof U-values must meet current standards; this is what drives most of the insulation work above.
• Structural — any altered opening (the old garage door) needs a sized lintel or structural calculation, signed off by an engineer where load-bearing.
• Fire safety — a fire door and fire-resisting separation between an integral or attached garage and the rest of the house, particularly if any part of the space stays in mixed use.
• Ventilation — trickle vents and, for any wet room, mechanical extract.
• Electrics (Part P) — rewiring to current regulations, typically on a new circuit from the consumer unit.
• Drainage (Part H) — required if you're adding a bathroom, kitchenette or utility room.

Skipping Building Regs is a common cause of problems at sale — an unregistered garage conversion routinely holds up conveyancing until retrospective sign-off (or a lawful development certificate) is obtained.

Integral, attached or detached — does it change the process?

• Integral garage (under the main roofline, part of the house footprint) — the most straightforward conversion; usually no external wall changes beyond the door opening, and PD is most likely to apply.
• Attached garage (built onto the side of the house, own roof) — similar process, but check whether the roof, walls or foundations are shared with a neighbour on a semi-detached or terraced property; if so, the Party Wall etc. Act 1996 may apply. See our party wall service.
• Detached garage — needs its own services run out from the house (electrics, water, drainage if a wet room), which adds cost. If it's to be used as fully independent living accommodation rather than an extension of the house, planning treatment changes — always check first.

Worked example: converting a single integral garage in a London terrace (2026)

Indicative 2026 London figures for a 16 m² integral garage converted to a dry room (bedroom or office). Add a bathroom and this typically rises by £12,000–£18,000.

Does a garage conversion add value to a London home?

Converting a garage into habitable space adds value in most cases — surveys of UK homeowners put the average uplift at around 10% for an extra bedroom, rising toward 20% where an en-suite bathroom is added, and around 7.5% for a home office conversion, which is also one of the cheapest conversions to carry out. Because London property values are higher than the UK average, the same percentage translates into a larger cash uplift here than elsewhere.

The one factor that can work against you: loss of off-street parking. In parts of London with Controlled Parking Zones or genuine parking scarcity, a garage or driveway space carries real value in its own right, and removing it can offset — or in a few cases exceed — the value the extra room adds. Get a local estate agent's read on how parking is valued on your specific street before committing, especially if the garage is your only off-street space.

How to keep a garage conversion on budget

• Get the floor and damp-proofing priced properly up front — this is the item cheap quotes most often shortcut, and the one that causes problems later.
• Confirm whether you need a Lawful Development Certificate before starting, not after — it protects you at sale.
• Use a fixed-price contract, not day rates, and get a proper Bill of Quantities so every quote is pricing the same scope.
• If you're adding a bathroom or kitchenette, involve interior design early so drainage, layout and fittings are coordinated on the drawings, not decided on site.
• Compare against a full refurbishment or house extension if you need more than one extra room — a garage conversion is the cheapest single-room option, but it's still worth pricing the alternative.