Planning a home extension, loft conversion or new windows in Hounslow? Many projects in London fall under permitted development and need no application at all — but Hounslow, like every local planning authority, decides applications against national rules and its own local plan. Knowing which route applies before you spend on drawings is the difference between a smooth project and a costly refusal.
Do you need planning permission in Hounslow?
For a typical house (not a flat or listed building) you can often extend under permitted development if you stay within national limits, such as:
- A single-storey rear extension up to 3m deep (terraced/semi) or 4m (detached) — up to 6m/8m under the Larger Home Extension prior-approval route.
- A maximum height of 4m for a single-storey rear extension, and no more than half the width of the original house for a side extension.
- Materials similar to the existing house, and nothing forward of the principal elevation facing a highway.
- No more than 50% of the land around the original house covered by extensions and outbuildings.
Local factors matter in Hounslow: conservation areas, Article 4 directions and listed buildings can remove permitted-development rights street by street, so always check the council’s position for your specific address.
How Hounslow assesses a planning application
Where permission is needed, Hounslow weighs your proposal against the National Planning Policy Framework (NPPF) and its local plan. The recurring tests are impact on neighbours (loss of light, overlooking and overbearing impact), design and character, overdevelopment of the plot, parking and trees. Most refusals come down to these — design to them from the start.
Check your Hounslow scheme before you apply
Unformed’s Planning Review reads your drawings, checks them against permitted-development (GPDO) and NPPF rules, researches how councils have decided similar cases for your postcode, and returns a risk-ranked report of what’s likely to be flagged in Hounslow — and how to fix it — before you submit.
For the official position, use GOV.UK to find Hounslow council and the Planning Portal to submit an application or a Lawful Development Certificate.
Related guides
- Do I need planning permission for an extension?
- Permitted development rights explained
- What is a Lawful Development Certificate?
- How to avoid a planning refusal
This page is general information, not legal or planning advice. Rules change and Hounslow applies them to each site’s circumstances — always confirm with the council before starting work. Unformed’s Planning Review gives an AI-assisted risk assessment and does not guarantee any planning outcome.