Garage Conversion with a Room Above | Two Storey Extensions

What you get

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.

It suits you if…

Your attached garage is used for storage, not parking
You need a ground-floor room and an extra bedroom
You want to keep all of your garden
Your garage walls or roof are in poor condition and need work anyway

Line drawing: existing house in outline, new work in brick, blue dashed line at first-floor level.

Design points that matter

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.

Infilling the garage door

The garage door opening is usually filled with a new wall and a window, on a new foundation, with brick to match. The new front wall needs a cavity, insulation and a damp-proof course, and the window position should line up with the room above.

Raising and insulating the floor

Garage floors are usually lower than the house and have no insulation or damp-proof membrane. We raise the floor to meet the house level where possible, with insulation and a membrane, so the converted room is warm and dry and does not have a step down.

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.

Planning and approvals by nation

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.

Wales

In Wales, a room above a side garage can be permitted development if the result is at least 10.5 m from the boundary opposite the side wall, set back 1 m from the front and adds no more than 50% to the width. Many garages fail this, so a householder application costing £585 is often needed. The conversion follows the Welsh Approved Documents.

Approval in Wales: Householder planning application: £585. Councils normally decide householder applications within 8 weeks.

Building regulations: Building regulations approval under the Welsh Approved Documents, which differ from England's in places (notably energy efficiency).

Scotland

In Scotland, building a room over a garage creates an extension of more than one storey, so Class 1B and its 10 m boundary test apply. Most attached garages need a householder application, which costs £371 and is decided within two months. The garage conversion and the room above both need a building warrant.

Approval in Scotland: Householder planning application: £371. Councils have two months to decide a local planning application.

Building standards: A building warrant from the council's building standards service before work starts, and a completion certificate at the end. Scotland uses its own Technical Handbooks.

Northern Ireland

In Northern Ireland, a room above a side garage normally needs a planning application, which costs £347 per dwelling, because two-storey permitted development is set out for rear extensions. The garage conversion and the new first floor both need building control approval from the council under the Technical Booklets.

Approval in Northern Ireland: Planning application for works to a house: £347. Councils aim to decide local applications within an average of 15 weeks; many take longer.

Building control: Building control approval from the local council under the Building Regulations (Northern Ireland), using the Technical Booklets.

Guide price

As a guide, the room above costs £31,500–£46,000 including VAT at 20% for 3 m × 6 m of new first-floor space (18 m²), with the garage conversion below priced after the survey, based on West Midlands prices and our Standard spec; London and the South East are higher.

Guide prices by region
Region	Per m² of new floor	Typical project
London	£2,100–£3,060 per m²	£38,000–£55,000
South East England	£1,930–£2,800 per m²	£34,500–£50,500
East of England	£1,800–£2,630 per m²	£32,500–£47,500
South West England	£1,800–£2,630 per m²	£32,500–£47,500
West Midlands	£1,750–£2,550 per m²	£31,500–£46,000
East Midlands	£1,720–£2,500 per m²	£31,000–£45,000
North West England	£1,660–£2,420 per m²	£30,000–£43,500
Yorkshire and the Humber	£1,610–£2,350 per m²	£29,000–£42,000
North East England	£1,580–£2,300 per m²	£28,500–£41,500
Wales	£1,610–£2,350 per m²	£29,000–£42,000
Scotland	£1,640–£2,400 per m²	£29,500–£43,000
Northern Ireland	£1,540–£2,240 per m²	£27,500–£40,500

Typical project: 3 m × 6 m of new first-floor space (18 m²), for the room above; converting the garage itself is priced after the survey. Including VAT at 20%, Standard spec. Essential spec is about 8% less, Premium about 20% more. See all prices and fees or work out your own guide price.

What's included

Free site visit, including a first look at the garage
Trial hole and structural assessment
Design for both floors together
Planning application or permitted development check
Foundations, walls, insulation and damp-proofing
Building regulations approval for the conversion and the room above
The build, carried out by vetted teams working under S&K

How it works

Free site visit
We look at your house, the boundaries, access and drains, and talk through what you need the new space to do.
Design and approval
Measured survey and drawings, then planning permission or a lawful development certificate, depending on the rules where you live.
Engineering and fixed price
Structural calculations and building regulations approval, then a fixed build price in writing.
Build and sign-off
Vetted teams working under S&K build it, and we arrange the completion certificate.

Questions about garage conversions with a room above

Is it worth converting the garage at the same time as building above it?

Usually, yes. Building a room above often means upgrading the garage foundations and walls anyway, so converting it at the same time spreads that cost over two rooms. You also have one period of disruption, one set of drawings and one building regulations approval instead of two.

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 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.

How warm will a converted garage be?

As warm as the rest of the house, if it is built properly. In England the new walls, floor and roof must meet limiting U-values of 0.18 W/m²K for walls and floors and 0.15 for roofs, and new windows 1.4. We add insulation and a damp-proof membrane, and extend the heating.

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.

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