How to choose the best garage conversion companies in the UK (2026)

Who actually does garage conversions

There is no such thing as a certified “garage conversion specialist”, and no credible national ranking of firms. The work is done by three kinds of contractor. General building firms handle it as a small project and are usually the safest choice when the job involves structural changes. Conversion specialists do them repeatedly, often at a keen fixed price, and are efficient on standard single garages. Multi-trade one-man operations can be excellent value but frequently under-price the regulatory side — which is exactly where conversions go wrong.

The question that sorts them quickly is: who is submitting the Building Regulations application, and how are you achieving the floor build-up? A contractor who answers both confidently and specifically has done this properly before.

Accreditations worth checking

Ask separately about insurance-backed warranties and public liability cover. On a conversion, the risk you most want covered is a damp or condensation problem appearing a year later.

The Building Regulations that decide whether it works

Converting a garage into a habitable room is a material change of use, so Building Regulations approval is always required — through a full plans application or a building notice with your local authority building control or an approved inspector. These are the areas that matter most, and the ones a weak quote skates over:

• Floor level and damp. Garage floors are usually laid lower than the house and often have no damp-proof membrane. The floor typically has to be built up with a new membrane lapped into the wall damp-proof course and insulation below the finished surface. Getting this wrong is the single most common cause of a damp, cold conversion — and it eats headroom, so it must be designed in from the start.
• Wall insulation. Many garages are single-skin brickwork, which cannot simply be plastered. Expect an internal insulated stud wall or insulated board system, with a cavity behind to manage moisture. This loses some floor area, which should be shown on the drawings.
• Roof insulation. Flat or lean-to garage roofs usually need insulating to meet current thermal standards, with proper ventilation above the insulation or a warm-roof build-up.
• Ventilation. Habitable rooms need background ventilation and rapid ventilation — in practice, trickle vents and an openable window, or mechanical extraction if it becomes a shower room or kitchen.
• Fire safety. Interlinked smoke alarms, a suitable escape window where required, and, on an integral garage, an appropriately fire-rated door between the new room and the rest of the house.
• Structure. Infilling the garage door opening usually means building a new wall beneath the existing lintel, off an adequate foundation. If the opening is being altered or widened, a structural engineer’s calculations are likely.
• Electrics and heating. New circuits are notifiable under Part P; extending heating into the room needs to be sized properly rather than an afterthought.

Planning permission: usually not needed, but check

Converting a garage that is attached to your house into a habitable room is normally permitted development, provided the work is internal and does not enlarge the building. That said, planning permission (or at least a formal check) is genuinely needed in several common situations:

• A planning condition on the original permission requiring the garage to be retained for parking. This is very common on estates built in the last thirty years and is the reason most garage conversions get refused retrospectively.
• An Article 4 direction covering your area, which removes permitted development rights.
• Listed buildings and conservation areas, where external changes are tightly controlled.
• Flats and maisonettes, which do not have permitted development rights.
• Creating a separate dwelling or annexe with independent living facilities, which is a change of use requiring permission.
• Detached garages in some circumstances, and any conversion that alters the external appearance substantially.

Checking is cheap and quick: your council can confirm the conditions attached to your property, and a Lawful Development Certificate gives you documented certainty for a modest fee. Do this before signing a contract, not after.

What a garage conversion costs in 2026

As a rule of thumb, most conversions land between £1,000 and £1,800 per square metre in 2026. A standard single garage runs two to five weeks on site. Be wary of anyone quoting well below these ranges — it almost always means the floor build-up, insulation or Building Regs fee has been left out.

Comparing quotes and spotting the gaps

• Is the Building Regulations application and fee included, and who submits it?
• What is the floor build-up, and what finished floor level and ceiling height will I end up with?
• How are the walls insulated, and how much internal width will I lose?
• Is the infill wall built off a proper foundation, and does the external finish match the house?
• Are heating, electrics and ventilation priced, or listed as provisional sums?
• Does the price include plastering, flooring and decoration, or does it stop at bare walls?
• What happens to the up-and-over door and its frame, and to any services running through the garage?

Send the same written brief to three contractors so the comparison is fair. Our garage conversion quotes form puts a consistent specification in front of several vetted builders at once.

One thing to think about before you start

You are permanently giving up a parking space and a good deal of storage. In areas with limited on-street parking that can count against the property when you sell, and the garage door opening being bricked up can look obviously converted from the street if the brickwork and window are not detailed sympathetically. A competent contractor will discuss both with you at survey stage. If in doubt, ask a local estate agent what conversions do to values on your particular street — the answer varies enormously by area.

FAQs: garage conversions in the UK (2026)