What the guide assumes
A sound existing structure, suitable services and space to insulate above the existing slab. Basic fit-out, infilling the garage-door opening and wall insulation are included.
SOUTHAMPTON, WINCHESTER & SURROUNDING AREAS
How much does a garage conversion cost?
Compare guide prices by garage type and see what affects the cost.
BUDGET BY GARAGE TYPE
Guide prices by garage type
The figures below are Checkatrade’s UK guide prices, updated May 2026. Each range is before VAT; allow for VAT when considering your total budget.
| Type of conversion | Guide price, excluding VAT | Basis |
|---|---|---|
| Integral | £10,000–£14,000 | Within the house footprint, around 16 m² |
| Attached | £10,000–£20,000 | Joined to the house, around 16 m² |
| Detached | £15,000–£25,000 | Separate from the house, around 16 m² |
| Double | £20,500–£45,000 | Around 36 m²; lower end integral, upper end detached |
| Partial | £5,500–£8,500 | Only part of the garage converted |
Source: Checkatrade’s garage conversion cost guide, May 2026
What needs separate pricing
Moving meters, new external-wall doorways and kitchen or bathroom fittings are excluded. Detached services, structural alterations and professional fees need particular attention.
Use these figures to plan your budget. The cost of an individual project depends on the property and the proposed work.
Request a quoteWHAT CHANGES THE PRICE?
What could affect your price?
1. The existing garage
The condition of the roof, walls and floor can change the amount of preparation and repair. Damp, uneven levels or an unsuitable existing structure need to be understood before the work can be accurately priced.
2. New openings
Replacing a garage door, adding windows or opening into the house affects the building work. Where loads need to be supported, the design and any structural calculations belong in the budget too.
3. Insulation and heating
The room needs an appropriate approach to heat loss, moisture and ventilation. The existing construction affects the options for a comfortable room.
4. Plumbing and drainage
A home office has different requirements from a room with a shower or utility area. The position and availability of services can make a substantial difference to the work involved.
5. Windows and finishes
Glazing, doors, flooring, fitted storage and decoration vary widely in price. The choice of products affects the overall budget.
6. Design and approvals
Drawings, engineering input, applications and inspections may be charged separately. These costs can sit alongside the construction budget.
Garage conversion cost FAQs
Is a garage conversion cheaper than an extension?
Using an existing structure can reduce some of the work associated with building an extension. It is not a guarantee of a lower cost: the garage’s condition, structural changes and specification still matter. Compare options against the room you actually need.
Can you give a price from photographs?
Photographs and a description help us understand the initial enquiry. A reliable quotation needs a clear description of the work and enough information about the existing building. The information needed depends on the project.
Should I get drawings before getting in touch?
Send any details you already have and tell us whether drawings or approvals are ready. You can enquire while you are still exploring your options.
GET A QUOTE
Ready for a quote for your conversion?
Send your project details and preferred start date.