Not all building projects require planning permission, but it's always best to check with your local planning authority

Not all building work requires planning permission – Permitted development rights, detailed in The Town and Country Planning (General Permitted Development) Order, 1997, allows for the extension of, or changes to, a property without planning permission, within certain strict guidelines.

Permitted Development Rights withdrawn –  local planning authorities have the right to remove some of your permitted development rights. This will mean that you have to submit a planning application for work which normally does not need one.

You will need planning permission if the planned addition is higher than the highest part of the roof of the ‘original house’ (as it was originally built) or if any part of the extension is more than 4m high and is within 2m of any boundary of your property.

You’ll also need permission if the volume of the ‘original’ semi-detached or detached house will be increased by more than 70 cubic metres. Volume is calculated from the external dimensions of the entire structure of the extension: length x breadth x height.

For a terraced house (including an end of terrace), or any house in a Conservation Area, a National Park, an Area of Outstanding Natural Beauty (AONB) or the Broads, you’ll need permission if the volume of the ‘original house’ would be increased by more than 10 per cent or 50 cubic metres (whichever is the greatest).

Altering a listed building requires two different permissions – planning permission and listed building consent. Permitted development rights do not apply to listed buildings.

Flats don't benefit from permitted development rights and planning permission is required for any extension.

Garages and other buildings within 5m of the house are considered to be extensions and follow the rules above. Garages more than 5m away from any dwelling are  classed as outbuildings.

Small porches do not require planning permission if they measure below 3 sq metres and are not higher than 3m. The porch must have a 2m clearance from the public highway.

Any previous extensions will have already used up some of your permitted development rights quota.

Some newer developments have their permitted development rights removed by a condition on the original planning permission. Check if your house falls into this category.

In certain areas permitted development rights are restricted or completely removed. These are for properties in Conservation Areas, National Parks, Areas of Outstanding Natural Beauty, listed buildings or other areas designated by your local authority.

For further advice on planning permission, download Planning: A Guide for Housebuilders from the www.odpm.gov.uk, or pick up a hard copy from your local planning office.

Words: Yasmin Gibson   Images: Jefferson Smith