Single story extension size?

For a single storey rear extension to be considered permitted development, that is , planning permission is not required, you can go, as a rule of thumb up to 6 m from orinal house rear wall, i.e. if the original house has already an extension of 3 m you can only go for another 3 m extension as a max., if the house still as original then you have your 6 m extension available, however there are restrictions for that: -No more than half the area of land around the "original house" would be covered by additions or other buildings, otherways you will need to adjust the extension measurements to accomplish this restriction. -There is what is called the neighbour consultation scheme, this means that large extensions where you are trying to use most of the length permitted, let’s say of over four and up to six metres, must go through the neighbour consultation scheme. If your neighbours raise any concerns or objections, the local authority will decide if their objections reveal any impact on the amenity of the neighbouring properties and whether your plans can go ahead. -There are areas where there may be a planning condition called Article 4 Direction, or other restriction that limits permitted development rights, that is, in these cases, you will need to apply for planning permission since this conditions withdraw permitted development. I hope that helps. Regards Fausto ACTP LTD

Under the new regulations the an extension can have the potential to be 6m in length providing that it does not take up more than 50% of the garden space. There are other parameters which need to be addressed but a architect would be able to assist you with or you local authority planning office.

They can apply for 6m extension under prior notification application which has some parameter like garden area( no more than half area of land around the original house would be covered by additions or other building, neighbours lighting impact, the maximum height should be less than 4m for pitch roof and 3m for flat roof and eaves and ridge height of extension no higher than 3m. the second option is apply for 3m under permitted development.

Check planning portal on the internet that will tell you everything you are allowed to do with your property type