Advice · Peterborough & Stamford

Do I Need Planning Permission for a House Extension?

Most single-storey extensions in Peterborough go ahead without a planning application, thanks to permitted development rights. The catch is that those rights come with strict size limits, and plenty of homes have had them removed or restricted without the owner realising. Here is how to work out where your project stands before you spend money on drawings.

Published 4 September 2026

What permitted development actually allows

Permitted development is a national set of rules that lets you extend a house without applying for planning permission, provided the extension stays within fixed limits. It applies to houses only, not flats or maisonettes, and only to the original house as it stood in 1948 or when first built. Any previous extension, even one added by a former owner, eats into your allowance.

The limits that matter most for a typical rear extension are below. If your plans sit inside all of them, you can usually build without an application, though we still recommend applying for a Lawful Development Certificate so you have proof when you come to sell.

  • Single-storey rear extension: up to 4 metres deep on a detached house, 3 metres on a semi or terrace
  • Larger rear extension of 6 or 8 metres respectively, but only after a prior approval application where neighbours are consulted
  • Maximum height of 4 metres for a single-storey rear extension, or 3 metres if within 2 metres of a boundary
  • Side extensions no wider than half the width of the original house and single storey only
  • Total footprint of all extensions and outbuildings no more than 50 percent of the land around the original house
  • Materials that look similar to the existing house, and no balconies or raised platforms

When you will need a full planning application

Two-storey extensions almost always need planning permission in practice, because the rules require them to be at least 7 metres from the rear boundary and no closer than 7 metres to any side boundary if they include a side element. Most plots in Werrington, Bretton, Orton and Hampton do not have that space.

Permitted development rights are also removed or reduced in several situations. Many newer estates around Peterborough, particularly Hampton Vale, Hampton Hargate and parts of Stanground South, had rights withdrawn by condition when the estate was originally approved. Homes in conservation areas such as Longthorpe, the Cathedral precincts, Barnack or Castor have tighter limits on side extensions and cladding. Listed buildings need listed building consent for almost any change.

If any of these apply, or your extension breaches a limit above, you will need a householder planning application to Peterborough City Council. The fee is currently a few hundred pounds, and the statutory decision period is 8 weeks, though you should allow 10 to 12 weeks from submission to be realistic.

Building Regulations apply either way

Planning permission and Building Regulations are two separate things, and this catches a lot of people out. Even if your extension needs no planning application at all, it still needs Building Regulations approval covering structure, foundations, insulation, drainage, fire safety, ventilation and electrics.

You can apply through Peterborough City Council's building control team or through a private approved inspector. A full plans application is typically £600 to £1,200 for a single-storey extension depending on floor area, and an inspector visits at set stages: foundations, damp proof course, drains, structure and completion. Without a completion certificate you will struggle to sell the house or remortgage.

Checks worth doing before you commission drawings

A few hours of homework at this stage can save weeks later. Start with the planning history for your address on the council's online planning register, which will show any conditions attached to the original approval for your house. Check the title deeds for restrictive covenants, which are separate from planning and can still be enforced by a developer or neighbour.

If you share a wall or are building within 3 metres of a neighbour's foundations, the Party Wall Act applies and you must serve notice at least two months before starting. Peterborough's clay soils also mean foundations are often deeper than people expect, particularly near mature trees, and that affects both your budget and what building control will accept.

  • Look up your property on the Peterborough City Council planning register
  • Check your deeds for covenants requiring consent from a developer or landlord
  • Measure the original house footprint, not the current one, when working out your 50 percent limit
  • Ask the council for informal pre-application advice if you are near a limit or in a conservation area
  • Speak to neighbours early, since objections carry more weight than most people think
FAQ

Common questions.

Can I extend without planning permission if my house is in Hampton?

Often not, because many Hampton estates had permitted development rights removed when they were built. Check the original planning conditions on the council register before assuming you can proceed.

What happens if I build without permission and it turns out I needed it?

The council can serve an enforcement notice requiring you to alter or remove the extension. You can apply for retrospective permission, but there is no guarantee it will be granted, and unauthorised work will show up in a buyer's searches.

How long does a Lawful Development Certificate take?

Peterborough City Council has a target of 8 weeks for a certificate of lawfulness. It costs roughly half a standard householder application fee and gives you written confirmation that your extension does not need planning permission.

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