Extensions over a garage in Billingham

Before you start in Billingham, here's what applies.

Postcode districts: TS20, TS22 and TS23
County / area: County Durham, England
Price region: North East England
Guide price: £28,500–£41,500 (£1,580–£2,300 per m²)
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Nearest towns: Stockton-on-Tees (1.8 miles), Middlesbrough (2.4 miles), Thornaby-on-Tees (3.9 miles)
Distance to Darlington: about 11.3 miles
First visit: Free, no obligation

About an extension over a garage

An extension over a garage is a new first-floor room built on top of an existing attached garage, usually a bedroom, en-suite or study. It uses a footprint you already have, so it adds floor space without taking any garden. The garage walls and foundations often need strengthening or replacing to carry the new floor.

We cover postcode districts TS20, TS22 and TS23 in and around Billingham, along with neighbouring Stockton-on-Tees, Middlesbrough and Thornaby-on-Tees.

What it costs in Billingham

Using our North East England rates, an extension over a garage with 3 m × 6 m of new first-floor space (18 m²) comes to about £28,500–£41,500, including VAT. Bigger or more glazed designs cost more per m². Steelwork for wide openings is the item most likely to move the figure; we'll know once the engineer has designed it.

Spec	Per m²	3 m × 6 m of new first-floor space (18 m²)
Essential	£1,450–£2,110 per m²	£26,000–£38,000
Standard	£1,580–£2,300 per m²	£28,500–£41,500
Premium	£1,890–£2,750 per m²	£34,000–£49,500

Planning and building regulations in Billingham

In England, most garages sit beside the house, so building over one makes a two-storey extension beyond a side wall, which always needs planning permission. If the garage is at the rear, the 3 m and 7 m rules for two-storey rear extensions apply, measured from the original house. A householder application costs £548 (or £575 for applications made from 8 December 2026).

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.

Design points for Billingham homes

Garage walls and the door opening

Garage walls are often a single skin of brick or block with piers, and the wide door opening needs a beam over it. Many over-garage extensions need new inner walls or a steel frame to carry the floor and to insulate properly, which we confirm before the design is fixed.

Matching the house

A room over a garage usually sits beside the front of the house in full view, so roof form, ridge height, windows and brick matter. Setting the front wall and ridge back slightly from the main house usually helps it look as if it belongs.

How we'd run your project

Understand the brief
At your home in Billingham we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Get it approved
Once you're happy with the design we submit it to the council for Billingham and deal with any questions from the planning officer.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Questions about extensions over a garage in Billingham

Which postcodes do you cover around Billingham?

We cover Billingham (TS20, TS22 and TS23) and nearby places including Stockton-on-Tees, Middlesbrough and Thornaby-on-Tees, plus the rest of County Durham. The first site visit is free.

Do I need planning permission for an extension over a garage in Billingham?

Billingham is in England, so England planning rules apply. Planning permission is needed: in England, permitted development only allows single-storey extensions to the side. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

How long does an extension over a garage take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils should decide householder applications within 8 weeks of validation), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.

Can I add an en-suite above the garage?

Yes, and it is a common choice for a main bedroom. The en-suite needs an extract fan under Part F, a route for the soil pipe down to the drains and enough fall for the waste, which can be harder over a garage. We plan the pipe route through the garage or an outside wall early.

How do I get into a room over the garage?

Usually through a new opening off the existing landing or a bedroom, so the stairs stay where they are. If the floor levels do not match, a step or two may be needed inside the new room. Where a landing opening is not practical, a new stair from a converted garage is an option.

Nearby

Close to Billingham? We work across the area, including:

Other extensions in Billingham

All two-storey extension services in Billingham · Extensions over a garage across County Durham

Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Billingham.