Two-storey side extensions in New Mills

New Mills: the key facts for this kind of project.

Postcode districts: SK22 and SK23
County / area: Derbyshire, England
Price region: East Midlands
Guide price: £84,500–£113,000 (£2,010–£2,700 per m²)
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Nearest towns: Marple (3.3 miles), Poynton (4.9 miles), Hazel Grove (5 miles)
Distance to Derby: about 37.5 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 New Mills (SK22 and SK23) and the places around it, including Marple (3.3 miles), Poynton (4.9 miles) and Hazel Grove.

What it costs in New Mills

Most of the cost of a two-storey side extension is set by its size and specification. For New Mills and the rest of the East Midlands, our guide is £2,010–£2,700 per m² including VAT, so about £84,500–£113,000 for a 3 m × 7 m footprint on two floors (42 m² of new floor space). 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	A 3 m × 7 m footprint on two floors (42 m² of new floor space)
Essential	£1,850–£2,480 per m²	£77,500–£104,000
Standard	£2,010–£2,700 per m²	£84,500–£113,000
Premium	£2,410–£3,230 per m²	£101,500–£136,000

Planning and building regulations in New Mills

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 New Mills homes

Avoiding a terracing effect

Where semi-detached houses sit close together, side extensions on neighbouring houses can join up and turn a row of pairs into a terrace. Many councils ask for a gap to the boundary at first floor to stop this, so we check local guidance before fixing the width.

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

Start at your house
We come to your home in New Mills, measure up, check the ground floor walls and roof structure, and note anything near the boundaries.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering New Mills.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.

Questions about two-storey side extensions in New Mills

Which postcodes do you cover around New Mills?

We cover New Mills (SK22 and SK23) and nearby places including Marple, Poynton and Hazel Grove, plus the rest of Derbyshire. The first site visit is free.

Do I need planning permission for a two-storey side extension in New Mills?

New Mills 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.

Who handles building regulations for a project in New Mills?

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 New Mills?

Our guide for the East Midlands, which covers New Mills, is £2,010–£2,700 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 £84,500–£113,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

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

The same service in neighbouring towns:

Other extensions in New Mills

All two-storey extension services in New Mills · Two-storey side extensions across Derbyshire

Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.