Do You Need Planning Permission for a Single Storey Extension?

Permitted development: when you can skip a planning application

Many rear single storey extensions are covered by permitted development rights, which means no full planning application is needed. For a detached house you can usually extend up to 4 metres from the original rear wall, and for a semi or terrace the limit is 3 metres. Under the larger home extension route these can go to 8 metres and 6 metres respectively, but that requires a prior approval notification to Burnley Borough Council first.

Height matters too. A single storey rear extension must not exceed 4 metres to the ridge, and where it sits within 2 metres of a boundary the eaves height is capped at 3 metres. It also cannot cover more than half the land around the original house.

• Detached: up to 4m rear projection (8m with prior approval)
• Semi or terraced: up to 3m rear projection (6m with prior approval)
• Maximum height 4m, eaves 3m near a boundary
• Cannot extend beyond the front or side elevation facing a road

When you almost certainly will need permission

Permitted development rights are removed in some situations, and this catches a lot of people out. If your property is a listed building, or sits within a conservation area, you should assume an application is needed. Flats and maisonettes have no permitted development rights at all.

It is also worth checking whether an Article 4 direction applies to your street, as these strip out permitted development on certain terraces and estates. Some newer developments around Burnley and Padiham carry planning conditions from the original build that do the same thing, so the original decision notice is worth digging out.

Building regulations apply either way

This is the part people forget. Even when your extension needs no planning permission, it still has to meet building regulations covering foundations, damp proofing, insulation, structural support over openings and drainage. That means a building control inspection process, either through the council or an approved inspector.

If you are building near a shared boundary you may also need a Party Wall agreement with your neighbour, and if the extension covers or runs close to a public sewer you could need a build over agreement with United Utilities. These are straightforward to sort out early but expensive to ignore.

The sensible order of things

The cheapest mistake to avoid is building first and asking questions later. A Lawful Development Certificate from the council, typically costing around 120 pounds, gives you written confirmation that your extension is permitted development, which is invaluable when you come to sell.

We generally advise confirming the planning position, then sorting building control and any party wall or drainage matters, before a single brick is laid. Getting this sequence right keeps the project moving and avoids stop-start delays on site.