Two-storey side extensions in Bentley

Bentley: the key facts for this kind of project.

Postcode districts: DN5
County / area: South Yorkshire, England
Price region: Yorkshire and the Humber
Guide price: £79,000–£106,500 (£1,890–£2,530 per m²)
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Nearest towns: Doncaster (1.1 miles), Adwick le Street (2.9 miles), Kirk Sandall (3.9 miles)
Distance to Sheffield: about 16.6 miles
First visit: Free, no obligation

About a two-storey side extension

A two-storey side extension is a new two-floor addition built into the space beside your house, often over a driveway or side passage. It typically adds one or two bedrooms upstairs and a utility, study or larger kitchen below, without giving up rear garden.

We cover Bentley (DN5) and the places around it, including Doncaster (1.1 miles), Adwick le Street (2.9 miles) and Kirk Sandall.

What it costs in Bentley

Using our Yorkshire and the Humber rates, a two-storey side extension with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £79,000–£106,500, including VAT. Bigger or more glazed designs cost more per m². Keep a contingency of around 10% for things nobody can see until the ground is opened up.

Spec	Per m²	A 3 m × 7 m footprint on two floors (42 m² of new floor space)
Essential	£1,740–£2,330 per m²	£73,000–£98,000
Standard	£1,890–£2,530 per m²	£79,000–£106,500
Premium	£2,260–£3,040 per m²	£95,000–£127,500

Planning and building regulations in Bentley

In England, a two-storey side extension always needs householder planning permission, because permitted development only allows single-storey extensions beyond a side wall. The fee is £548 (or £575 for applications made from 8 December 2026), and councils should decide within 8 weeks of validation. Expect them to look at set-back, roof height, gaps to the boundary and the effect on neighbours.

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 Bentley homes

Set-down and set-back

Councils usually want a two-storey side extension to look subordinate to the house. Setting the front wall back from the main front and dropping the ridge slightly below the main roof helps it read as an addition, and is often expected in local design guidance.

Side windows, boundaries and gutters

Upstairs windows in the side wall face the neighbour, so they are usually obscure-glazed and fixed, or left out. Building close to the boundary also raises questions about foundations, overhanging gutters and access for maintenance, so we design the eaves and gutter to stay within your land.

How we'd run your project

Measure and listen
A visit to Bentley to understand how you live in the house now and what the extra rooms need to do, plus a first look at the structure.
Get it approved
Once you're happy with the design we submit it to the council for Bentley and deal with any questions from the planning officer.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Questions about two-storey side extensions in Bentley

Who handles building regulations for a project in Bentley?

We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

How much does a two-storey side extension cost in Bentley?

Our guide for Yorkshire and the Humber, which covers Bentley, is £1,890–£2,530 per m² including VAT. A typical project with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £79,000–£106,500. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Which postcodes do you cover around Bentley?

We cover Bentley (DN5) and nearby places including Doncaster, Adwick le Street and Kirk Sandall, plus the rest of South Yorkshire. The first site visit is free.

How long does a two-storey side extension 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 build a two-storey side extension over my driveway?

Yes, if the drive is wide enough for a useful room and the council accepts the design. You may lose off-road parking, which some councils weigh up, and the foundations need to suit the ground below. We check parking, drains and meter positions at the free site visit before any drawings are prepared.

Nearby

Other towns near Bentley:

Other extensions in Bentley

All two-storey extension services in Bentley · Two-storey side extensions across South Yorkshire

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