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  • Writer's pictureMortgage Tree

When Would I need planning permission?

Getting planning permission for that dream extension or for essential maintenance can be a nightmare. Planning regulation is complex and many people have fallen into the pitfalls that await the ill-informed. As a starting point, we’ve distilled some key facts about what building projects do and don’t need planning permission …

If you want to build something new or make a major change to your building you will probably need planning permission. If your project needs planning permission and you do the work without getting it, you can be served an enforcement notice ordering you to undo all the changes you have made. So don’t risk it and check before you start.


An addition or extension to your house* is generally considered to be permitted development. So you won’t need to go through the additional hassle of getting planning permission as long as:

  • Your extension is no more than half the area of land around the original house (curtilage). The “original house” is seen as it was in 1948; after this date how it was newly built

  • Your extension is not forward of the principal elevation or side elevation onto a highway

  • Your extension is not higher than the highest part of the roof

  • In the case of single storey extensions, it must not extend beyond the rear wall of the original house by more than eight metres for a detached house, or more then six metres for any other house

  • The maximum height of your single-storey rear extension is not higher than four metres

  • Extensions of more than one storey do not extend beyond the rear wall of the original house by more than three metres

  • Side extensions are single storey with maximum height of four metres and width no more than half that of the original house

  • Two-storey extensions are no closer than seven metres to rear boundary

  • The materials are similar in appearance to the existing house

  • Your extension does not include verandas, balconies or raised platforms

  • Any upper-floor, side-facing windows are obscure-glazed; any opening is 1.7m above the floor

Conservatories are categorised as the same as any other extension, as set out above.

*Different rules apply to flats and maisonettes.

There are also different planning restrictions for designated areas such as Conservation Areas and if your property is listed. So check with your Local Planning Authority

Garages, sheds and other outbuildings

Outbuildings such as sheds, garages, greenhouses and some other structures are also considered to be permitted development. You can build a garage or outbuilding on your property without planning permission as long as it’s of a reasonable size – no higher than 4 metres. Do bear in mind though that outbuildings cannot take up more than half of the land around the original property. There are as always exceptions where planning permission is necessary so contact your Local Planning Authority or visit the Planning Portal for further details of planning exemptions for outbuildings.

Paving over the front garden

As long as the material you are using is porous there is no need for planning permission whatever the size of the new hardstanding. However if the material is impermeable anything over 5 square metres requires planning permission.

Windows and doors

In most cases there is no need for planning permission to repair or replace windows and doors. The major exception is if your property is listed in which case you will have to obtain listed building consent. And don’t forget you will need Building Control approval for windows.

External walls and roof

For minor maintenance works, or improvements such as painting your house or inserting a skylight, you do not need planning permission. As always this is not the case if your building is listed. If you live in a conservation area or an area of outstanding natural beauty, you are required to obtain planning permission if you wish to change the appearance of your home. If you live in a flat and you wish to alter the roof you should consult the local planning authority before you start any work.

Wind turbines and solar panels

Temporary wind turbines do not require planning permission but permanent ones usually do. If you are unsure contact your local authority. Solar panels do not require planning permission unless you live in a listed property.

Fences, gates, and walls

Planning permission is necessary for any fence, gate, or wall:

  • Next to a road and over 1 metre high

  • Over 2 metres and not next to a road

  • If your house is listed

  • If it forms a boundary with a listed building

Trees and hedges

  • Many trees are protected by tree preservation orders and you will need permission to prune them. You can phone your council to check if any trees on your land are protected.

  • Similarly permission is required for work done to any trees in conservation areas. To find out if a tree on your property is protected contact your local council.

  • Hedges can be any height but you are responsible for any hedge on your property – it’s your job to stop them becoming a nuisance to your neighbours


Nearly all internal works such as loft conversions, garage conversions, new staircases, bathrooms, kitchens, or rewiring, do not require planning permission. But, do check if you want to do anything to a listed property or you live within a Conservation area.

How to get planning permission

According to our 2019 Annual HomeOwner Survey, 27% of homeowners – or 4.7 million people – said planning permission is a major obstacle to getting home renovations done. So how do you ensure problems with planning permission don’t put a stop to your plans?

Unless you already have a local architect designing and submitting your plans, and one with a track record of obtaining planning permission in your area, a good planning consultant can be helpful in determining local planning restrictions, targets and preferences to ensure your project is tailored accordingly. They can help you to get planning permission.

They may suggest you start with an informal meeting with your local planning authority (LPA) before you submit an application. Some local planning authorities charge for this service. A pre-planning application meeting can help the LPA in dealing with your planning application when it is formally submitted.

Ahead of this meeting you will need to have proposals and plans of what you want to do. Be ready to describe your proposals and if possible show the LPA designs – with current floor plans and proposed new design. According to the Planning Portal it’s a good idea at this meeting to:

  • Ask for an assessment of whether there is a reasonable chance of getting planning permission

  • Discuss site problems such as roads, footpaths, power cables, watercourses, sewers and telephone lines

  • Ask about potential problems such as noise and traffic, and whether the council might impose conditions to overcome these problems rather than refuse planning permission.

Planning application drawings

A key point in the process of getting planning permission is creating your design drawings. Whether it’s a small straightforward single storey extension on the back of your house, or something more ambitious, you will need a set of accurate floor plans for your designs and elevations (which show the vertical view of your design internally and externally).

These drawings need to be produced to the appropriate scale and demonstrate how your project will be in keeping with it’s surroundings. You can do the design drawings yourself or use a local architect’s firm that specialises in obtaining planning permission.

As well as your designs, you are likely to need technical drawings in order to get building regulations approval (see below) and for your builder. These provide in depth plans for each element of your project and materials that should be used. A structural engineer can look a your existing and proposed plans and advise on the building materials required and whether any reinforcements are needed and if so where. They can also produce the technical drawings you will need.

And don’t forget…

  • Building regulations: Whether you need planning permission or not, your building work still needs to comply with building regulations, for your safety, to improve the energy efficiency of your home (and reduce bills) and to ensure you can sell your house in future without any costly problems or delays.Make it clear to whoever carries out your building work that you expect them to ensure their work is compliant with building regulations but be warned: responsibility ultimately lies with the building owner, who may be served a notice to pull down or alter the work if it doesn’t comply with the building regulations. Read more about this in our guide Do I need Building Regulations Approval?

  • Party wall: You also need to be aware that if you have a shared party wall with your neighbour, you may require a party wall agreement


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