Cutting Back Projecting Part of Recently Built Party Wall – Who Bares the Cost?

Question

My neighbours built an extension and in the process they built a party wall astride the party line. The wall was built that way with our permission and on the condition that they would bear all the costs for the wall, but that the wall once built would become a jointly owned party wall that we could use for any building work in the future.

The neighbours’ extension was built though in such a way that our side (as opposed to their side) of the new wall bears the bottom of their roof and thus the gutter hangs over on our side.
 
If we are building a similar extension on our side, we need to cut back the bottom of that roof a bit and make a gutter in the valley between the roofs on top of the middle of the party wall, so that we can support our similar roof on the side of the party wall that is sitting on our side of the party line.
 
I am told that the costs for cutting back that roof should be the borne by the neighbours, but before I decide if I will do that, where is that requirement for them to pay the costs arranged in the law? I don’t seem to be able to find it in the Party Wall etc. Act of 1996.

Answer

There is nothing in the Party Wall Act that says the neighbours must cut back the projecting parts of the roof structure – that would be dealt with as a trespass at common law.

Are you aware that you will have to compensate the neighbours for the cost of building the wall (Section 11(11) of the Act) should you make use of it in the future unless you have some agreement that they will waive that right.