Extensions over a garage in Conisbrough
For an extension over a garage in Conisbrough, the first questions are always the same: how big, which approvals, and what it will cost. This page answers all three for South Yorkshire.
Quick reference for homeowners in Conisbrough.
- Postcode districts
- DN12
- County / area
- South Yorkshire, England
- Price region
- Yorkshire and the Humber
- Guide price
- £29,000–£42,000 (£1,610–£2,350 per m²)
- Approval route
- Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
- Nearest towns
- Mexborough (2.6 miles), Bolton-upon-Dearne (4.2 miles), Maltby (4.7 miles)
- Distance to Sheffield
- about 11.8 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 district DN12 in and around Conisbrough, along with neighbouring Mexborough, Bolton-upon-Dearne and Maltby.
What it costs in Conisbrough
A guide price for Conisbrough: around £29,000–£42,000 for 3 m × 6 m of new first-floor space (18 m²). That works out at £1,610–£2,350 per m² of new floor space, including VAT at 20%. Design fees, structural calculations and approval fees are separate and listed on our prices page.
| Spec | Per m² | 3 m × 6 m of new first-floor space (18 m²) |
|---|---|---|
| Essential | £1,480–£2,160 per m² | £26,500–£39,000 |
| Standard | £1,610–£2,350 per m² | £29,000–£42,000 |
| Premium | £1,930–£2,820 per m² | £35,000–£50,500 |
Planning and building regulations in Conisbrough
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 Conisbrough homes
Floor levels and headroom
Garage floors are often lower than the house, and the new first floor may not line up with the existing landing. We set the floor level to avoid awkward steps upstairs, while keeping enough headroom in the garage below for a car or storage.
Fire separation
If the garage stays a garage, the floor between it and the room above, and any door into the house, must give fire separation under building regulations. That usually means fire-resisting plasterboard ceilings, sealed gaps and a fire door, which we design in from the start.
How we'd run your project
Visit and first ideas
One of our team visits your house in Conisbrough, checks the walls, roof and drains, and sketches out options with you.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
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 and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.
Questions about extensions over a garage in Conisbrough
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.
Do I need planning permission for an extension over a garage in Conisbrough?
Conisbrough 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 much does an extension over a garage cost in Conisbrough?
Our guide for Yorkshire and the Humber, which covers Conisbrough, is £1,610–£2,350 per m² including VAT. A typical project with 3 m × 6 m of new first-floor space (18 m²) comes to about £29,000–£42,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Can my garage take a room on top?
Sometimes, but it needs checking. Many garages are built on shallow footings with thin walls, designed only for a single storey. We dig a trial hole and inspect the walls, and the structural engineer decides whether to reuse them, strengthen them, underpin the footings or build new foundations inside the garage.
Do I need to convert the garage as well?
No. You can keep the garage for parking or storage and build only the room above, as long as the floor between them and any door into the house meet fire separation rules. Converting the garage at the same time is often good value, because the walls and foundations may be upgraded anyway.
Nearby
Close to Conisbrough? We work across the area, including:
Other extensions in Conisbrough
- Rear
- Side
- Wraparound
- Part two-storey
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Conisbrough · Extensions over a garage across South Yorkshire
Tell us about your house in Conisbrough and we'll call you back to arrange a free, no-obligation visit.