Single-storey rear extensions must not extend beyond the rear wall of the original house by more than three metres (if a semi-detached house) or by four metres (if a detached house). Anything more than three metres and you would require planning permission for the extension.Click to see full answer. Simply so, what is the maximum extension without planning permission?The permitted development rules have recently been relaxed, allowing you to build an extension without planning permission of up to six metres (or eight metres if your house is detached).Subsequently, question is, do you have to get planning permission for an extension? Extensions. 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). Likewise, can I build a single storey extension without planning permission? As long as you stay within the below parameters, you can build a single-storey extension without needing planning permission: The extension does not sit forward of the principal elevation. Materials should be similar. Side extensions are not permitted on Article 1(5) Land (e.g. AONB, Conservation Areas)What size extension can you build under permitted development?If you are planning and designing a single storey extension, this means it can be up to 6m from the original rear wall of an attached house (or 8m on a detached property) and up to 4m in height. If your extension is to be within 2m of your property’s boundary, the eaves height is limited to 3m.
