Leaking extension roof

[ceri]

Pitched kitchen extension roof leaking at ceiling corner and further along the same wall.. The wall adjoins my neighbour's extension (terraced houses on a hill). Roofer said a new roof and replacement lead valley would solve  the problem.  It was leaking again within a year of the new roof. Roofer inspected it but had no idea why and did not attempt to fix it.  The photos of the ceiling inside are 3 years since the new roof . It doesn't always noticeably leak after rain and seems to be a gradual  thing. The valley has been cleaned twice since the new roof was done so blockage or debris  is not the cause.  Eventually it will make a hole in the ceiling and rot the felt as it did before the new roof.  Other roofers have looked at it and all said different things. Any ideas of cause and solution please?

[Eric]

Is it possible to get a closer picture where the pitched roof meets the neighbours extension?

 

it may need a better valley made against the extension, possibly with fall to keep the water moving.

 

Others will chime in 

[ceri]

Thanks. I will try to upload something better.