Planning permission for home extensions and conversions

Find out whether you need planning permission for a home extension, conservatory, outbuilding or conversion here.

Check whether you need planning
permission for an extension or conversion

Building an extension or converting unused areas of your home is a great way to create space, add value to your property and avoid having to move home entirely. But before you begin to plan that new conservatory or loft conversion, you will need to check whether you need planning permission.

Matt Thomson, Director of Policy and Partnerships from the Royal Town Planning Institute says that: “There are permitted developments for things like loft conversions or conservatories. Getting planning permission for other projects can be a slow and painful process though.”

You should check with your local authority if you plan any building work on a listed property, in a conservation area, national park, world heritage site or area of outstanding natural beauty. Planning regulations operate under the provision that you do not extend more than 50% of the size of the original house.

It can be a good idea to consult a professional architect, surveyor or builder to check whether your plans will be permitted. Architect Claire Haigh, from Claire Haigh Associates in Brighton says: “When a client contacts me, I will go and have a look at the property, discuss their requirements and let them know whether they need planning permission.”

So what are the planning rules for converting or extending your home?

Planning permission for extensions – extensions are permitted but there are many rules to adhere to. In general, materials should be similar to those of the original house and you can’t build any verandas, balconies or raised platforms. The extension, including the eaves and ridge height, should not be higher than the highest part of the roof or forward of the principal elevation or side elevation fronting a highway. If the extension is within two metres of a boundary, the eaves should not be higher than three metres.

A single storey rear extension – must not be higher than four metres or extend beyond the back wall by more than three metres for an attached house and four metres for a detached home.

Extensions are a permitted development
as long as you meet set requirements

A more than one storey extension – should be no closer than one metre to the rear boundary of the property and the roof pitch should match the existing building. The maximum depth of a rear extension of this kind should be no more than three metres beyond the rear wall.

Side extensions – must be single storey with a maximum height of four metres and a width of no more than half that of the original house. Any upper floor side facing windows should be obscure glazed and openings 1.7 metres above the floor.

Planning permission for outbuildings – this category includes sheds, greenhouses, garages and buildings or enclosures for pools, saunas, ponds or kennels. Outbuildings do not require planning permission provided that they are no more than four metres tall with a dual pitched roof or three metres for any other roof. They should be single storey, have no verandas or balconies and not be built on land forward of a wall forming the principle elevation.

Planning permission for conservatories – are also permitted as long as they don’t face onto a highway, are not higher than the original roof or more than four metres in height. They must not extend more than three metres beyond the rear wall in an attached house and four metres in detached homes. Conservatories built onto the side of homes must be single storey with no verandas or balconies.

Planning permission for a porch – as long as the porch is built on a ground floor area not exceeding three metres squared, is no more than three metres high and not built within two metres of any boundary, it will be permitted.

Conservatories are permitted
by planning authorities

Planning permission for a loft conversion – planning is permitted as long as your loft conversion adds no more than 40 metre squared of space for a terraced home or 50 metre squared for detached home. The conversion should not reach higher than the original roof, should use similar materials and include no verandas, balconies or raised platforms. Any side facing windows should also be obscure-glazed and openings should be 1.7 metres above the floor.

Planning permission for a basement conversion – if you are just converting an existing basement you won’t need planning permission as long it won’t be used as a completely separate unit. You will have to gain permission if you need to dig up parts of the road or pavement or want to add a light well.

Source: Planning Portal