Garage conversions with a room above in Northamptonshire

Northamptonshire at a glance

Nation: England
Price region: East Midlands
Postcode areas: LE, NN
Towns covered: 9 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 Northamptonshire we cover Northampton (NN1), Corby (NN17), Kettering (NN14), Wellingborough (NN8), Rushden (NN9) and Daventry (NN11), plus the smaller places around them.

Guide price in the East Midlands

Our guide for the East Midlands is £1,720–£2,500 per m² including VAT. On a project with 3 m × 6 m of new first-floor space (18 m²), that puts a garage conversion with a room above in Northamptonshire at roughly £31,000–£45,000 (for the room above; converting the garage itself is priced after the survey). Professional fees for drawings and the structural engineer are listed separately on our prices page.

Spec	Per m²	Typical project
Essential	£1,580–£2,300 per m²	£28,500–£41,500
Standard	£1,720–£2,500 per m²	£31,000–£45,000
Premium	£2,060–£3,000 per m²	£37,000–£54,000

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

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.

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.

How we work in Northamptonshire

Understand the brief
At your home in Northamptonshire we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in England before drawing in detail.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Finish and certify
Second fix, plastering and making good, then building control's final inspection and the completion paperwork.

Towns we cover in Northamptonshire

Garage conversions with a room above in Northamptonshire: questions

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

In the East Midlands our guide is £1,720–£2,500 per m² including VAT, so about £31,000–£45,000 (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.

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.

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.

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 Northamptonshire?

Northamptonshire 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 Northamptonshire · About garage conversions with a room above