Can You Build an Extension Without Planning Permission in Lancashire?

What permitted development allows

Permitted development rights let houses (not flats or maisonettes) be extended within set limits without applying for planning permission. The limits are measured from the house as it was originally built, or as it stood on 1 July 1948 if it is older. Any extension added since then, even by a previous owner, counts towards your allowance.

For a single storey rear extension, the main limits are:

• Up to 3m deep on a terraced or semi detached house, or 4m on a detached house
• No more than 4m high overall, and no higher than 3m at the eaves if it is within 2m of a boundary
• Side extensions must be single storey, no taller than 4m, and no wider than half the width of the original house
• Extensions and outbuildings together must not cover more than half of the land around the house
• Materials should look similar to the existing house, such as matching stone or brick

Terraced houses and back yards

Much of Burnley, Nelson, Colne and Accrington is Victorian stone terraces with small back yards. On these houses the 50% coverage rule often matters more than the 3m depth limit. If the original back offshoot already takes up part of the yard, you may have little or nothing left to extend into. It is also common for the old kitchen outrigger to be part of the original house, which changes where the 3m is measured from.

A two storey rear extension can also count as permitted development. It is limited to 3m deep and must be at least 7m from the rear boundary. On most terraces with back streets, that 7m distance rules it out.

When permitted development rights do not apply

Several situations remove or restrict these rights, and they are common across Lancashire:

• Conservation areas, such as parts of central Burnley, Worsthorne, Hurstwood, Barrowford and Clitheroe, where side extensions and some cladding need permission
• The Forest of Bowland National Landscape, which has similar restrictions
• Listed buildings, which need listed building consent for almost any alteration
• Newer estates where the original planning permission removed permitted development rights by condition
• Areas covered by an Article 4 direction from the local council

Larger extensions and getting certainty

Under the larger home extension scheme, you can build a single storey rear extension up to 6m deep on a semi or terrace, or 8m on a detached house. You have to apply to the council for prior approval first. The council writes to your neighbours, and you must wait for a decision, which can take up to 42 days, before starting.

Even if you are sure your plans fit the rules, we recommend applying for a Lawful Development Certificate from Burnley, Pendle, Hyndburn or whichever council covers you. The fee is half the normal householder planning fee. The certificate proves the extension was lawful, which solicitors will ask about when you come to sell. It usually takes around eight weeks.

Building regulations and neighbours still apply

Not needing planning permission does not mean you can skip building regulations. Foundations, drainage, insulation, structural steels, fire safety and ventilation all need approval, either from your council's building control team or an approved inspector. If you are building close to a public sewer, which happens often with terraced houses, you may also need a build over agreement with United Utilities.

If you are building on or near a shared boundary wall, the Party Wall Act means you need to serve notice on your neighbours. As a very rough guide, single storey extensions in this part of Lancashire tend to cost somewhere between £1,800 and £2,600 per square metre for a standard finish. The final figure depends on ground conditions, access, steelwork and the kitchen or bathroom fit out.