Extension in Dorset
Do you need planning permission for a single-storey extension in Dorset? Here is what the permitted development rules say, how Dorset Council’s designations change them, and what decides an application — grounded in the official guidance, quoted verbatim.
Do you need planning permission for a single-storey extension in Dorset?
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 Dorset this matters: the borough has 311 conservation areas and 78 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.
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 →
How Dorset’s designations apply
| Designation in Dorset | Published |
|---|---|
| Conservation areas | 311 |
| Article 4 directions (PD removed) | 78 |
| Listed building outlines | 8,904 |
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.
What Dorset 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.
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.
Get a planning report for your Dorset address
A Planning Policy report reads the designations on your exact Dorset address, quotes the Dorset Council and national policies that apply to a single-storey extension, and — on Pro — shows decided applications nearby with outcomes.