Do I Need Permission to Extend?


Can you extend?

  • You will need the freeholder’s/landlord’s permission and should check your deeds to ensure there are no restrictive covenants.

  • If you live in a semi-detached home you may have to serve your neighbours with a party wall notice in order to extend. The Party Wall Act 1996 allows you to undertake work on your property while protecting your neighbours’ rights too. A legal requirement, it applies to any wall between two semi-detached houses: if your building works could affect such a wall then you will need to serve this notice on your neighbour.

  • Most, but 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.

  • 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 3m high and is within 2m of any boundary of your property.

  • Single storey extensions cannot exceed 4m in height, 4m in depth for a detached house and 3m for any other type of house.

  • Rear extensions of more than one storey should not be closer than 7m to the rear boundary and should not exceed 3m.

  • Side extensions may be single storey with a maximum height of 4m and its width must not be more than half the width of the original house.

  • You may not extend a property at the front or side if it faces a highway.

  • Materials used need to be similar to those of the existing house, with the exception of conservatories.

  • Flats do not 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.

  • Bear in mind that 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.

  • If your project is daring, ask a planning officer for feedback before submitting your design.

  • For the latest legislation visit Planning Portal and further advice on planning permission, download Planning: A Guide for Housebuilders from the, or pick up a hard copy from your local planning office.

How do I extend a listed building?

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

  • Always employ an architect to work on a historic building, and together liaise with the local council’s conservation officer before submitting your application – it will save you time in the long run.

  • Be aware that your new addition should not dominate the existing listed building – it must complement it, though this doesn’t mean that a new extension cannot be modern.

  • Conservation officers are more likely to approve sympathetic modern additions than pastiche.

  • The quality of your new extension must match that of your existing home, or you risk your application being refused.

The planning process

  • It's strongly recommend that you obtain planning permission, where necessary. If in doubt contact your local council’s planning department as it will take drastic action against unacceptable development.

  • You can apply for planning permission on your own or your architect can act on your behalf. If you don’t have an architect, a planning advisor can help you.

  • Once the council has received your plans, it will notify neighbours and place the plans on the Planning Register for any member of the public to view. A committee made up of councillors will either make a decision or appoint a senior planning officer to make one, which can take eight weeks.

  • If planning permission is granted, you normally have five years in which to carry out the planned works. If permission is denied, you can amend your plans to comply with the council’s requirements and re-apply. You do not have to pay a further fee if your amended plans are submitted within 12 months. You can appeal within three months of the council’s decision.

  • For online planning applications visit

  • To view a simple explanation of the planning process click here.

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