Window up to the boundary line - impact future extension?

Hey, Unfortunately I can not see the image Ill give you some info from experience. 1.The local council can tell you to have an offset of 1.5m from their window in order to allow daylight in. Its a first come first serve type of situation. 2. There isn't enough information to assume its illegal build, check with building reg's to see if windows are placed there without consent. This can help you with point 1. 3. If they have built on the property line there should be a party wall agreement. Which then again should clarify any points such as the windows. 4. Contact your local planning department send them a picture and request information about any applications. ( unless its pd try this with building regs department ) honestly is a bit of a mess without proper information there isn't a lot I can do. Hope this helps.

Permitted development still requires a building notice to be submitted, to do this, you still need plans drawn up by an Architect, these are then submitted to your local Building Control office with an application and small fee, if they’ve done all this for their proposed extension, then the window may have been approved. If they’ve had FULL Planning permission granted, then the window will have been approved also. You can check on your local council website for the planning status. If it’s a very small window either clear glass or obscure glass, I wouldn’t get stressed about it and risk a lifelong neighbour feud and awkwardness. They probably are unaware of your concerns? Talk to them, they may be able to put a roof window instead, with a vaulted ceiling. Hope this helps.