Permitted Development & Planning Permission

The most important stage of an extension project is the design stage when you need to decide whether your project falls within permitted development or needs planning permission. This can decide the size and type of project you choose, as a project requiring planning permission needs more time to design and construct, than a project which falls within permitted development. For a home or kitchen extension, there are strict parameters for permitted development, which allows you to build without requiring permission from your local council.

Permitted development are a set of design specifications that if your project follows, allows you to add an extension without needing to ask permission from the local council. If your project differs from these and goes over them, then you must apply for planning permission from your local building authority which can take up to 8 weeks. For a home or kitchen extension, permitted development restrictions are as follows:

All Extensions

• You can only build on up to half of the land around the original house (as the house was originally built, without any extensions) as an extension or with other buildings.
• The extension must not be higher than the highest part of the existing roof.
• If you are within two metres of a boundary to your neighbour’s property, the height at the eaves of the extension cannot be higher than three metres.
• Your extension cannot be built forward of the ‘principal elevation’ (the wall at the front of the house), or where it fronts a highway, the ‘side elevation’.
• Your extension cannot include a balcony, veranda, microwave antenna, a chimney or flue, or any alteration to the roof of the existing house.
• You cannot have exterior cladding if you are on designated land, such as a heritage site or conservation zone.
• The exterior material of the extension must be similar to the existing house.

Side Return Extensions

• Your extension cannot exceed four metres in height.
• Your extension can only be single storey.
• You can only build up to half the width of the original house.
• You cannot have a side extension if you are within designated land, for example conservation zones or heritage areas.

Single-Storey Extensions

• Your extension cannot extend beyond the rear wall of the house by more than four metres if you have a detached house, or three metres for other houses.
• If you are not on designated land or a Site of Special Scientific Interest, the limit for a single-storey rear extension is increased to 8 metres for a detached house or 6 metres for other houses. Local Planning Authority must be informed of the proposed work via a prior approval application.
• Your extension cannot exceed four metres in height.

Multi-Storey Extensions

• Your extension must not extend beyond the rear wall of the original house by more than 3 metres or be within 7 metres of any boundary opposite the rear wall.
• The pitch of the extension roof must match the existing house as much as possible.
• Your upper-floor extension must have obscure-glazed windows in the side elevation and must be non-opening unless it is higher than 1.7 metres above the floor.
• All side extensions of more than one storey will need planning permission.
• All rear extensions of more than one storey that are on designated land will need planning permission.

When your surveyor visits your home for a site survey, they will discuss what can be done within these restrictions or whether your extension needs to go through your local council. If your project needs planning permission, your architect will make these applications on your behalf after you have confirmed the design you want for your extension. It is important that you are certain on the plans made, as they will be harder to change later down the process.

An application for planning permission will take 8 weeks to be approved or denied in most cases. In the situation that your plans are denied, Simply Extend will amend your plans free of charge to reapply for planning permission. We cannot guarantee a project will be approved by your local planning authority, but we have many years of experience and can accurately estimate whether a project will gain approval.

If you live within a conservation area or heritage zone, you will almost always have to apply or planning permission from your council for an extension project. Our architects have lots of experience planning extensions in these areas and will use other projects in your area to gauge whether approval will be gained for your extension.

If you are thinking about having a loft conversion, contact a member of the Simply Extend team today on 0800 917 7571!