side return extension longer than 3m?

[mummmypirate]

We live in an edwardian semi with a side return on our joined side. We'd like to fill it with a single storey extension and roof lantern in the ceiling. The new building would be right up against the boundary so would require a party wall agreement. Our neighbours are supportive because they'd like to do something similar but I'm concerned that we still won't get planning because the infill would be almost 7 metres long. The 3 metres you're allowed under permitted development will only open up half the length of the existing kitchen so isn't a great option. Anyone had any experience of this? Seems planning laws don't make it very easy to develop dingy underused side returns because of their long thin shape.

You will have a better chance of gaining planning if your neighbor will do a similar job together so that your infill extension would not cause any lose of light issue to him. I would hire an Architect to draw up planning drawings for both you and your neighbor and submit for a full planning application. Bear in mind that your neighbor does not have to carry out the extension together if he fancies doing it later. but of course, it will save you 2 money if build together. Whats the wide of the extension? it should be less than half the width of the return building. Call your local council to confirm this and see what they think.

Thanks Hong. The side return is 3.5 m wide - together with next door our houses make a 'u' shape - we want to infill the U, with a 3.5m high parapet party wall along the boundary. It's currently a 2m brick wall.

We're considering a joint application but my understanding is that building work has to commence simultaneously for permission to be valid, this concerns me because I worry about our project being tied to next door's finances.

You may be able to get away from that timing restriction if you and your neighbor submit separate application but reflect the proposal next door. Make sure you inform the planning officer about it.

ok so the existing "L" is 3.5m, what is width of the infill on your side? thats what the planning will consider.

I have already commented on another thread by mummy. In my experience such an application would have to be made jointly, and would at least be subject to a condition on the planning permission that the work be undertaken at the same time, if not by way of a legal agreement under the planning acts. If the extension would be harmful to the neighbouring property without the 'other half' being built, then the Council would not allow for the possibility of the development being undertaken in isolation.

Thanks for replying. Hong, our proposed infill would be 3.5m wide by 6.8 long this would be mirrored by our neighbour on the other side of the party wall. This would bring the new 'orangery' flush with the existing back wall of our kitchen, squaring off the rear of our house...

... which brings me to another question. To be acceptable, must new extensions always be subordinate to the existing house? i.e. should the extension be set back/ stepped from the existing rear wall, and if so, by how much?

Ok, if your proposed infill is 3.5m and the existing L building at the back of the house is 3.5m as well then the planning officer may consider it as excessive extension. But don't take my word for it and you should call up council to confirm their local policy.

What you are asking in your 2nd question is that you can design it to fall under permitted development so that you don't need to submit a full planning application, meaning you are permitted to build it as long as you follow the guideline. This includes stepped extension: 3m ext off the far rear wall and 3m ext off the infill wall in the U void. Again, check with your local planning office.