My wife and I are looking at a house which would require a decent extension off the back to make it a decent family sized home, my question is as it is semi detached would we be allowed to build an extension without pp where it hugs the boundary of the side of the property where the house is joined the the neighbouring property as I’ve seen planning rules that state if the extension is closer then 2m to a boundary it needs planning permission. Surely that doesn’t make sense if one side of the house is already touching that boundary as it’s semi detached.