How to Get Planning Permission for a House Extension: A Step-by-Step Guide

Before you can submit a planning application, you need a set of architectural drawings. These include existing and proposed floor plans, elevations (what the extension looks like from all sides), and a site location plan. You can commission an architect, architectural technologist, or use our Design & Build service — we handle drawings as part of our full service.

Each local council has its own planning portal and specific requirements. In our area, that's Basildon Borough Council, Castle Point Borough Council, Rochford District Council, Chelmsford City Council, or Brentwood Borough Council depending on where you live. Check their website for any local design guides or supplementary planning documents that might affect your application.

For larger or more complex projects, a pre-application enquiry lets you ask the planning department informally whether your proposal is likely to be approved — before you spend money on a full application. Most councils charge a fee (typically £50–£200) but it can save you from a costly refusal.

Applications are submitted online through the Planning Portal (planningportal.co.uk). You'll need to upload your drawings, complete the application form, and pay the fee. For a standard householder extension, the fee is currently £258 in England.

Once your application is validated, your council will notify your immediate neighbours and display a site notice. They have 21 days to submit comments or objections. The planning officer considers these alongside your application — but objections don't automatically mean refusal.

A planning officer is assigned to your application. They'll visit the site, assess the proposal against local planning policies, and consider any representations received. For straightforward householder applications, this process typically takes 6–8 weeks from validation.

The council issues a formal decision notice — either granting permission (with or without conditions) or refusing. If refused, you have the right to appeal to the Planning Inspectorate, or you can revise and resubmit. Resubmissions within 12 months of a refusal are free.

Planning permission is valid for 3 years from the date of approval. You must start construction within this period. Before you break ground, you'll also need Building Regulations approval — a separate process that covers how the extension is built, not just whether it can be.