David.S

A bit late for this thread but I'm an architect in East Dulwich and have just completed a side infill extension on my own house and on a clients house which are both the full length of the rear out-rigger at the back and against the party line of the neighbours property. The new permitted development rules help you if your neighbours don't raise an objection, if they do the council will probably ask for further details. The trick is to design the new party wall at a height that won't affect your neighbours enjoyment of their ground floor rear rooms. This is not a 'Right of Light' and has nothing to do with shadow, it is a measurement of 'Daylight'; basically the amount of daylight entering their rooms measured as a percentage. If there was an issue you would have to prove that the daylight entering their room hasn't dropped below a certain percentage which is a different amount depending on the use of the room. David