Hi there. How easy, difficult or likely is it to extend an existing rear shed dormer on a 1930s semi? We are the middle of 3 sets of semis. Both houses in the set on one side have dormers, like ours, where about a third or so of the roof has a dormer window with the remainder of the original roof unchanged and therefore sloping. Both houses in the set on the other side have dormers more typical of modern ones that go almost to the end of the roof. Photos attached. Am I right in thinking that as long as I remain within PD, it should be OK to extend like my neighbours in the other set? In fact we'd preferably like to go to within 20cm clear of the eaves as per PD, which would extend it out in width AND depth. Would the fact it would be extended forward of the attached neighbour's dormer be an issue? I think the houses were built with these dormers, so I'm not sure the neighbours that we want to copy have extended theirs, so don't know if that would make a difference. We're not in a conservation area or anything. Other surrounding houses are detached. Thanks guys.