Garage conversions with a room above in Wiltshire

Wiltshire at a glance

Nation: England
Price region: South West England
Postcode areas: BA, SN, SP
Towns covered: 14 listed below, plus surrounding villages
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Site visits: Free, no obligation

What a garage conversion with a room above involves

This service suits you if your attached garage is used for storage rather than parking and you need both a ground-floor room and an extra bedroom. You get a structural check of the garage, a design for both floors, the approvals your nation needs, insulation and damp-proofing to modern standards and the build, carried out by vetted teams working under S&K.

Across Wiltshire we cover Swindon (SN1), Salisbury (SP1), Trowbridge (BA14), Chippenham (SN15), Melksham (SN12) and Warminster (BA12), plus the smaller places around them.

Guide price in South West England

Guide prices for garage conversions with a room above in South West England are around £1,800–£2,630 per m² of new floor space, including VAT. For a typical project with 3 m × 6 m of new first-floor space (18 m²), that's roughly £32,500–£47,500 (for the room above; converting the garage itself is priced after the survey). Kitchens, bathroom fittings and flooring are priced separately so you can compare like with like.

Spec	Per m²	Typical project
Essential	£1,660–£2,420 per m²	£30,000–£43,500
Standard	£1,800–£2,630 per m²	£32,500–£47,500
Premium	£2,160–£3,150 per m²	£39,000–£56,500

Rules in England

In England, converting a garage on its own often needs no planning permission, but building a room above a side garage makes a two-storey extension beyond a side wall, which needs planning permission costing £548 (or £575 for applications made from 8 December 2026). Some estates have conditions removing garage conversion rights, which we check first.

Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.

Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.

The Party Wall etc. Act 1996 applies, so notices may be needed for work on or near a shared wall or boundary.

Getting the design right

Foundations and walls

Garage footings are often shallow and the walls are a single skin of brick or block. Carrying a new first floor usually means underpinning or new foundations, and new inner walls or a steel frame. Because the garage is being converted too, this work can be designed once for both floors.

Stairs and access

The room above is usually reached from the existing landing, while the converted garage opens off the hall. If the levels do not work, a new stair inside the converted garage can serve the room above, which we test in the layout.

How we work in Wiltshire

Understand the brief
At your home in Wiltshire we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Wiltshire.
Fixed price in writing
With approved drawings and calculations, we give you a fixed build price and a programme you can plan around.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.

Towns we cover in Wiltshire

Garage conversions with a room above in Wiltshire: questions

How much does a garage conversion with a room above cost in Wiltshire?

In South West England our guide is £1,800–£2,630 per m² including VAT, so about £32,500–£47,500 (for the room above; converting the garage itself is priced after the survey) for 3 m × 6 m of new first-floor space (18 m²). Essential and Premium specs move that by roughly 8% down or 20% up.

Does the room above need a fire door if the garage is converted?

Once the garage becomes a habitable room, the fire separation needed between a garage and the house usually falls away. The new bedroom above still needs an escape window or a protected route to the stairs, and smoke alarms. If you keep part of the garage for storage, separation may still be needed, which we confirm with building control.

Will losing the garage affect parking?

It can. If the garage counts towards required parking on your estate, the council may look at whether enough off-road spaces remain. Most households in practice park on the drive. We check your title and any planning conditions about the garage at the start.

Do I need planning permission to convert my garage?

In England, converting an attached garage to a room often needs no planning permission when the work is internal, unless a condition or Article 4 direction removes that right. Building regulations approval is always needed. The room above usually needs planning permission when the garage is at the side.

Will I need planning permission in Wiltshire?

Wiltshire is in England. Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.

Neighbouring areas

All extension services in Wiltshire · About garage conversions with a room above