Planning Policy

Extension in Stevenage

Do you need planning permission for a single-storey extension in Stevenage? Here is what the permitted development rules say, how Stevenage Borough Council’s designations change them, and what decides an application, grounded in the official guidance and quoted verbatim.

Modern glazed extension against a classical stone house
New glass against old stone: the extension question every authority weighs
The short answer

Do you need planning permission for a single-storey extension in Stevenage?

Many single-storey rear extensions are permitted development under Class A, within set limits on depth, height and how much of the garden they cover, so no planning application is needed. In Stevenage this matters: the borough has 7 conservation areas and 127 Article 4 directions, and inside those the permitted development route narrows or is removed, so a single-storey extension can need a full application where it would not two streets away.

1.0: The permitted development position

The starting point

Many single-storey rear extensions are permitted development under Class A, within set limits on depth, height and how much of the garden they cover, so no planning application is needed.

“This provides permitted development rights for the enlargement, improvement or other alteration of a house.”PD technical guidance, Class A · full text in the library → · official source →
2.0: What changes it in Stevenage

How Stevenage’s designations apply

Designation in StevenagePublished
Conservation areas7
Article 4 directions (PD removed)127
Listed building outlines0

Because extension depends on permitted development rights restricted on article 2(3) land, the conservation areas above are decisive: inside one, expect to need a full application. Counts are read live from planning.data.gov.uk; your report checks them against your exact address.

3.0: How it’s decided

What Stevenage weighs

Where an application is needed, design does the deciding: depth against the neighbouring rear walls, loss of light, roof form, and materials against the parent building.

Read the full extension guide →

4.0: A worked example

See a single-storey extension in a real report

London’s most common project: a kitchen extension behind a Victorian terrace in a conservation area with an Article 4 direction. 262 nearby decisions, 81% approved.

Read the rear extension in clapham case study →

Your report

Get a planning report for your Stevenage address

A Planning Policy report reads the designations on your exact Stevenage address, quotes the Stevenage Borough Council and national policies that apply to a single-storey extension, and (on Pro) shows decided applications nearby with outcomes.

5.0: Questions

Extension in Stevenage, answered

Do I need planning permission for a single-storey extension in Stevenage?
Many single-storey rear extensions are permitted development under Class A, within set limits on depth, height and how much of the garden they cover, so no planning application is needed. In Stevenage this matters: the borough has 7 conservation areas and 127 Article 4 directions, and inside those the permitted development route narrows or is removed, so a single-storey extension can need a full application where it would not two streets away.
Does a conservation area affect a single-storey extension in Stevenage?
Yes. extension relies on permitted development rights that are restricted on article 2(3) land, which includes conservation areas. Stevenage Borough Council has 7 of them, so inside a boundary you are more likely to need a full application.
How does Stevenage decide a extension application?
Where an application is needed, design does the deciding: depth against the neighbouring rear walls, loss of light, roof form, and materials against the parent building. A Planning Policy report quotes the specific Stevenage Borough Council Local Plan and national policies that apply, verbatim, and shows decided applications nearby.
6.0: More for Stevenage

Other projects in Stevenage