I've got a friend who is wanting to add an extension to the side of his house and build right up to the boundary with the neighbour. It fits within requirements of the PD regs and the planning office has confirmed that the extension itself is permitted development. However, the extension is a lean-to sloping towards the boundary. The planners say that, as the rainwater gutter will overhang the boundary of the property, it is not PD and the extension requires planning permission. Is this correct? Are they being petty? I can understand that the gutter overhanging the boundary needs to be addressed, but would have thought it comes under the Party Wall Act or is just a legal issue rather than a planning issue?