Planning Policy

Extension in Blackburn with Darwen

Do you need planning permission for a single-storey extension in Blackburn with Darwen? Here is what the permitted development rules say, how Blackburn with Darwen 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 Blackburn with Darwen?

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 Blackburn with Darwen this matters: the borough has 14 conservation areas, 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 Blackburn with Darwen

How Blackburn with Darwen’s designations apply

Designation in Blackburn with DarwenPublished
Conservation areas14
Article 4 directions (PD removed)0
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 Blackburn with Darwen 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 Blackburn with Darwen address

A Planning Policy report reads the designations on your exact Blackburn with Darwen address, quotes the Blackburn with Darwen 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 Blackburn with Darwen, answered

Do I need planning permission for a single-storey extension in Blackburn with Darwen?
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 Blackburn with Darwen this matters: the borough has 14 conservation areas, 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 Blackburn with Darwen?
Yes. extension relies on permitted development rights that are restricted on article 2(3) land, which includes conservation areas. Blackburn with Darwen Borough Council has 14 of them, so inside a boundary you are more likely to need a full application.
How does Blackburn with Darwen 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 Blackburn with Darwen Borough Council Local Plan and national policies that apply, verbatim, and shows decided applications nearby.
6.0: More for Blackburn with Darwen

Other projects in Blackburn with Darwen