Two-storey extensions for semi-detached houses in Peterborough

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

Postcode districts: PE1, PE2, PE3, PE4 and PE5
County / area: Cambridgeshire, England
Price region: East of England
Guide price: £57,500–£78,000 (£2,060–£2,780 per m²)
Approval route: Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); a two-storey side extension needs planning permission.
Nearest towns: Whittlesey (5.1 miles), Market Deeping (7.7 miles), Stamford (11.2 miles)
First visit: Free, no obligation

About a two-storey extension for a semi-detached house

A two-storey extension for a semi-detached house is a two-floor addition to the rear, the open side, or both, designed around the attached neighbour on one side. The rear is often the simplest option and can sometimes be permitted development, while a side extension uses the gap on the detached side. Both need care with the shared party wall and the neighbour's light.

We cover postcode districts PE1, PE2, PE3, PE4 and PE5 in and around Peterborough, along with neighbouring Whittlesey, Market Deeping and Stamford.

What it costs in Peterborough

Expect a two-storey extension for a semi-detached house in Peterborough to land somewhere around £57,500–£78,000 for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). Our East of England guide rate is £2,060–£2,780 per m², including VAT. We'll give you a written design-stage price first, then a fixed build price once the drawings are agreed.

Spec	Per m²	A 4 m × 3.5 m footprint on two floors (28 m² of new floor space)
Essential	£1,900–£2,560 per m²	£53,000–£71,500
Standard	£2,060–£2,780 per m²	£57,500–£78,000
Premium	£2,470–£3,340 per m²	£69,000–£93,500

Planning and building regulations in Peterborough

In England, a two-storey rear extension on a semi can be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary, with matching materials and roof pitch. A two-storey side or wraparound extension always needs planning permission, costing £548 (or £575 for applications made from 8 December 2026). Protected areas such as conservation areas exclude two-storey rear permitted development.

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 Peterborough homes

Rear, side or both

On a semi, a rear extension sits against the attached neighbour, while a side extension faces the detached neighbour and the street. We compare the space, cost and approval route for each, and for a wraparound, before you commit to one design.

The attached neighbour's light

A two-storey rear extension next to the party wall can take light from the neighbour's rear windows. Councils often use a 45-degree test, so the first floor may need to be shorter than the ground floor or set in from the shared boundary.

How we'd run your project

Free site visit
We visit your home in Peterborough, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Engineer it
Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.
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 two-storey extensions for semi-detached houses in Peterborough

How much does a two-storey extension for a semi-detached house cost in Peterborough?

Our guide for the East of England, which covers Peterborough, is £2,060–£2,780 per m² including VAT. A typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) comes to about £57,500–£78,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Do I need planning permission for a two-storey extension for a semi-detached house in Peterborough?

Peterborough is in England, so England planning rules apply. Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); a two-storey side extension needs planning permission. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

Which postcodes do you cover around Peterborough?

We cover Peterborough (PE1, PE2, PE3, PE4 and PE5) and nearby places including Whittlesey, Market Deeping and Stamford, plus the rest of Cambridgeshire. The first site visit is free.

Should I extend my semi to the side or the rear?

It depends on your plot and what you need. A rear extension keeps the side drive and can sometimes be permitted development, but it affects the attached neighbour. A side extension keeps the rear garden but always needs planning permission in England. We compare both at the free site visit.

Will a side extension make my semi look like a terrace?

It can if it fills the whole gap to the boundary at first floor and the neighbour does the same. Many councils ask for a first-floor gap to the side boundary or a set-back for this reason. We design the extension to keep the semi reading as one of a pair.

Nearby

The same service in neighbouring towns:

Other extensions in Peterborough

All two-storey extension services in Peterborough · Two-storey extensions for semi-detached houses across Cambridgeshire

Tell us about your house in Peterborough and we'll call you back to arrange a free, no-obligation visit.