The back of my property is in a corner and the water gathers in the gutter; as it has a long way to travel to the downpipe on the neighbors' side. This has caused damp to get into the wall behind. The neighbors downpipe has an offset that leads to a vent but also has a junction which allows the rainwater from the gutter to go into it (see pic). I was looking to have the same set-up on the downpipe and gutter on my side but I cannot find this fitting. Does anyone know what it's called or where to find one?
you do not want that arrangement, vent pipes to terminate 900 above eaves to prevent sewerage smells permeating through window openings
Afraid not, long term solution is new plastic guttering and downpipe at suitable location but thats not an easy option