Do I Need Planning Permission?

The two regimes

There are two separate regimes to think about. Planning permission is about whether you can build or extend at all, and what it can look like. Building Regulations are about how it is built — structural safety, fire, drainage, electrics. Many projects need Building Regulations approval even when they do not need planning permission. See our Building Regulations guide for that side.

What usually does NOT need planning permission

Under Permitted Development, you can usually do the following without applying for planning permission, provided you stay within size and height limits:

• •Small single-storey rear extensions (4m deep on a detached house, 3m on others).
• •Larger rear extensions up to 8m (detached) / 6m (others) under the neighbour consultation scheme.
• •Loft conversions up to 40m³ (terraced) or 50m³ (detached) of added volume.
• •Side extensions up to half the original width and single-storey only.
• •Outbuildings, garages and sheds up to 50% of the curtilage.
• •Some porches, dormer windows (at the rear) and rooflights.

When you DO need permission

You will usually need full planning permission if:

• •Your home is a flat or maisonette (no Permitted Development).
• •Your home is Listed or in a Conservation Area, National Park or AONB.
• •Your property has already had its Permitted Development rights removed by a condition on a previous planning permission.
• •The extension is larger than the Permitted Development limits.
• •You are changing the use of a building (for example, a shop to a home).
• •You are building a new, separate dwelling.

Getting certainty

If your project is within Permitted Development and you want proof for a future buyer, apply for a Lawful Development Certificate (LDC) from your council. It costs less than a full application and confirms the work is lawful. Always check the latest rules on gov.uk/planning-permission, as Permitted Development limits change.