My house is semi detached and on the join with the neighbouring side it's a 45 degrees extension with a gulley running down it. As you can see from the pics, the gulley edge is under the tile but doesn't seem to have much of a lip on it. Should the lip be higher to combat the increased flow of water during heavy rain or should it be mortared? There is water ingress in my bathroom roof when there is heavy rain and I've checked the tiles so I don't think they are the problem. The gulley is on my neighbours side.
Any thoughts?
Any thoughts?