Garage conversion cost in Southampton: the 2026 guide
Garage conversion cost in Southampton comes down to the UK guide range for your type of garage plus the council’s Building Control fee. Below is what the money buys and what moves it; a free survey then fixes the figure for your house.
(UK guide ranges)
Garage conversion prices in 2026, by garage type
Typical UK figures for each kind of garage, drawn on one scale for comparison. No two Southampton garages are identical, so the survey and a fixed quote always come before any commitment.
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Single garage conversion cost
£8,000 – £15,000
A one-bay garage beside a semi or detached house. A plain study or bedroom sits near the bottom of the range; extra circuits, a long radiator run and a better finish move it upward.
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Integral garage conversion cost
£10,000 – £14,000
Already inside the house, often below a bedroom, so the money goes on the front wall, lifting the floor, fire protection to the ceiling and a doorway from the hall.
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Double garage conversion cost
£15,000 – £25,000
Two bays of floor to insulate, line and heat. Dividing it into two rooms, or adding a shower room, takes a conversion towards the top of this range.
UK guide figures for 2026. Your own quote is fixed for your house and lists every item.
(Line by line)
What a garage conversion price should include
Our quotes list each part of the job separately. These are the lines behind a typical conversion around Southampton, so the destination of every pound is clear and other quotes can be held to the same standard.
- 01Listed
Survey and scale drawings
Measuring up, checking the slab, damp course, walls and drain runs, and drawing the room you want.
- 02Listed
Building Regulations
The application, the council or approver’s fee, and inspections at the footing, the insulation and completion.
- 03Listed
Footing, wall and window
A footing under the old door opening, a new wall built to suit the house, and a window sized for light and air, and for escape in a bedroom.
- 04Listed
Insulated floor
Damp-proof membrane, rigid insulation and a screed or boarded timber floor, lifted to meet the house floor.
- 05Listed
Wall and ceiling linings
Insulation and plasterboard over the existing walls and ceiling, bringing the room up to the thermal standards.
- 06Listed
Electrics and lighting
New sockets, switches and lights, tested and certified once the work is finished.
- 07Listed
Heating
Normally a radiator taken off the house heating and sized for the room.
- 08Listed
Doors and decoration
A doorway from the house (a fire door if the layout requires one), skirting, plaster and paint, ready to use.
- 09Listed
Outside works
Making good around the new wall, the edge of the drive and any drainage channel at the front.
(Cost factors)
What moves the cost of a garage conversion up or down
Eight things decide where a conversion sits within its guide range. Nearly all of them are visible at the survey, before you commit.
Get a free survey-
Can raise the price
Floor area and depth
Every extra square metre needs insulation, boarding, plaster and flooring. A deep garage running back beside the house costs more than a shallow one, even between neighbours on the same road.
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Can raise the price
How the slab sits
Garage slabs usually sit below the house floor, and many slope down to the door. A dry, flat slab keeps preparation simple; a slope, cracks or damp add work before the insulated floor goes down.
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Can raise the price
Filling the door opening
Every conversion needs a footing and a new wall where the door was. Matching older brick, render or tile hanging, or fitting a bay window, takes longer than plain brickwork and a standard casement.
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Can raise the price
Water and waste
Bedrooms and studies need wiring and heat only. Add a shower room, utility or kitchen and you also need supply pipes, a waste route that falls to the drains, and extraction: the largest single jump in cost.
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Can raise the price
Keeping it warm
Most rooms take a new radiator off the existing heating. Underfloor heating, a separate electric system or a boiler that cannot carry another radiator all add to the bill.
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Can lower the price
Converting only part
Keeping the front section as storage behind the existing door, with an insulated partition, leaves less floor and wall to finish and no new front wall to build.
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Can raise the price
Fittings and finish
Flooring, internal doors, lighting and joinery vary widely. The guide ranges assume a good standard; feature lighting, fitted storage or premium flooring sit higher.
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Shown in your quote
Approval fees
Every conversion needs Building Regulations approval. For 2026/27 Southampton & Eastleigh Building Control lists £454 for full plans and Test Valley £498 including VAT; New Forest quotes per job. Your quote shows the fee on its own line.
(Compared)
Garage conversion, extension or loft: what each one involves
Because the walls and roof already stand, a garage conversion normally costs less than an extension of similar floor area. The table sets out what each route really needs.
| Compared | Garage conversion | Single-storey extension | Loft conversion |
|---|---|---|---|
| Foundations | A footing under the new front wall only | New foundations under every new wall | Usually none; new joists carry the floor |
| Walls and roof | Already standing; insulated and lined | Built new | Roof altered for a dormer or roof windows |
| Planning permission | Not usually required | Depends on size and position | Often not required; bigger dormers may need it |
| Building Regulations | Required | Required | Required, including a new staircase |
| Garden | Untouched | Smaller | Untouched |
| What you lose | Garage storage or a parking space | Some garden | Loft storage and some headroom |
(Price questions)
Questions about price and fees
Plain answers on prices, council fees and what a quote covers. For anything else, give us a ring.
Call 07930 368740Why are garage conversion quotes so different?
Two garages that look alike can need very different work: one slab is flat and dry, another slopes and shows damp; one boiler can take another radiator, another cannot. Certain quotes omit the new front wall, the council fee or the decorating. An itemised quote lets you compare like with like.
Does adding a shower room cost more?
Yes. Beyond the floor, walls and wiring every room needs, it calls for hot and cold supplies, a waste run falling to the drains, mechanical extraction and tiling. That makes it the largest single extra, moving a conversion up towards the top of its guide range.
Is converting part of the garage cheaper?
Usually, because less floor, wall and ceiling is finished and the garage door stays. The front becomes a store for bikes and tools, with an insulated partition between it and the new room.
Are Building Control fees part of the price?
They appear as their own line. For 2026/27 Southampton & Eastleigh Building Control lists £454 for full plans or £452 for a building notice on a garage conversion; Test Valley charges £498 or £506 including VAT; New Forest District Council quotes per project. A structural engineer, if a beam is needed, is listed separately.
Do the guide prices include VAT?
The ranges are typical UK figures to help you budget, not quotes. Your written quote says plainly whether VAT is included, so the final invoice holds no surprises.
How can I keep the cost of a garage conversion down?
Choose a room without plumbing, such as a bedroom, study or playroom, take heating from the existing system and fit a standard window in the new wall. Converting just the rear and leaving a store at the front also lowers the cost.
Is there a charge for the survey?
No. The visit is free and you are under no obligation. We measure up, inspect the slab, walls and drainage, then send a fixed price with every item listed.
(Free survey)
Swap the guide range for a fixed figure.
Tell us where you are and what the garage should become. After a free visit you receive one fixed price with every item listed, and you decide in your own time.
- A home visit to measure and discuss the room
- Scale drawings with a fixed price, item by item
- Planning and Building Regulations checked for your address