Will I need planning permission?

'Will I need planning permission?' This is certainly one of the first questions you'll be asking if you want to extend or renovate your home or garden. 

Not all projects require you to go down the full planning permission route, which will often save you time and money. Instead, you'll be able to carry out some work under Permitted Development (PD) which allows you to build up to a certain size and undertake a number of building projects without planning.

Permitted Development is a different type of planning route. Its scope varies and PD covers internal and external works but there are rigorous requirements applying which are governed by factors such as size, height and your home’s surroundings, particularly highways and neighbouring properties. Your project must keep to these requirements to come within the scope of PD.

Always check with your local authority, builder or architect, before beginning a project, to make sure the works you are wanting to carry out fall under the relevant planning rules. 

if you live in a designated area, such as a Conservation Area, or own a listed building, PD rights often don't apply. Your property also has a limit to its Permitted Development rights, which don't change again when it changes ownership. So, if your home has already been extended, its Permitted Development rights have already been allocated.


Under PD rights you can build an extension without planning permission as long as you meet certain criteria.

You can extend a detached property by 8m to the rear if it’s a single-storey (6m for a semi or terraced house), or by 3m if it’s double

A single-storey extension can’t be higher than 4m on the ridge and the eaves, and ridge heights of any extension can’t be higher than the existing property

Two-storey extensions must not be closer than 7m to the rear boundary

Side extensions can only be single storey with a maximum height of 4m and a width no more than half of the original building

Any new extension must be built in the same or similar material to the existing dwelling

Extensions must not go forward of the building line of the original dwelling

In designated areas (such as areas of outstanding natural beauty, conservation areas), side extensions require planning permission and all rear extensions must be single storey

An extension must not result in more than half the garden being covered


Removing Internal Walls

It’s unlikely that you’ll need planning permission to do this but there are exceptions, particularly if your home is listed or in a conservation area, so it’s always worth asking your local authority. Even if you won’t need planning permission, you will need Building Regulations approval on structural and electrical work.

Replacing Windows

You won't usually require planning permission to add a new window, or door, into your home. This counts for replacing windows and moving them too. But if your building is listed, windows is one of the key areas where you may not be able to make a change, only replacing like for like. When it comes to inserting a new window on the upper storeys of the side elevation of your house, you'll require planning permission unless the windows are glazed with obscured glass to a standard of level 4 or 5 obscurity. They also must be a non-opening frame, unless 1.7m above the floor of the room the window is in. 

For new or bigger windows or doors, you will need to follow Building Regulations guidance and to choose the right window style.

Converting a Garage


If you're looking to convert an integral garage or any building attached to the main house, to turn it into a living space, it is likely to fall under Permitted Development. If the garage was built after the house, though, you'll need to check with your local authority that this addition hasn't used your home's Permitted Development allocation. 

Converting a detached garage is more likely to need planning permission. It will also require a change of use application under Planning Permission. 


Rooflights can be added under Permitted Development if they don't project more than 15cm from the slope of your roof. but if the rooflights would extend forward of the roof plane on the elevation fronting a highway, they are not permitted and will require formal planning permission. 

Rooflights are generally not permitted on a property which is located in a Conservation Area or an Area of Outstanding Natural Beauty under Permitted Development.

Loft Conversion

A loft conversion is a great way to add extra space and value to your home without the need for planning consent. While there are limitations on the cubic content allowed under permitted development, generally up to 40 cubic metres is fine.

When it comes to additional headroom in the loft space, PD allows for the construction of dormer windows. But, they must not sit higher than the highest part of the existing roof, or extend forward of the roof plane on the principal elevation.

Two-Storey Extension

Adding a two storey extension under Permitted Development is a relatively new idea, designed to help fast-track this sort of home improvement to create extra habitable space for homeowners. To qualify under PD rights, it must be at the rear of the dwelling (this includes adding a second storey onto an existing single storey part of the house).

The two storey extension must also not exceed 3m in depth or be within 7m of the rear boundary. There are some restrictions that apply to the design. Again check with your Local Authority.

New Conservatory

As for single storey extensions, conservatories fall under the same restrictions and can be added under PD. Conservatories stand alone from most extensions however, as they can generally be built without Building Regulations sign off, if they're under 30 square metres and have exterior grade doors separating them from the main house. 

Shed, Cabin, Garden Office or Outbuilding

There may be opportunities to build a number of outbuildings under PD, providing the total area covered by such buildings/enclosures does not exceed 50% of the total area of the property. This 50% should take into account any extensions, but not the area covered by the main house.

Outbuildings cannot sit forward of the principal elevation

There are height restrictions depending on the type of roof (4m for dual pitch roofs, 3m for other roofs, and 2.5m when the building is within 2m of the boundary)

Outbuildings may only be single storey, with the maximum eaves height remaining at 2.5m

Outbuildings under PD cannot be used for residential accommodation, e.g. bedrooms or an annexe, but can be used to provide a place to work from home.


Solar Panels

Solar panels can be added under PD, providing they do not protrude more than 200mm beyond the plane of the wall or roof, and that the highest part of the panel is not higher than the highest part of the roof (excluding the chimney). Limitations will apply in Conservation Areas and on listed buildings.


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Published on :  

January 29, 2024

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