Lead Gully overflows and leaks - I think

I have a leak in my roof along a lead gully but I can see no obvious hole. It seems that the water from one roof surface (the steeper one) comes down, and due to its speed overflows the lead on the opposite side of the gully. I am presuming the sides of the lead gully are not high enough to keep the water in.

Any suggestions on what I can do about this ? Can I repair it from inside ? Do I need to do a complete replacement, including the lead gully and make its sides steeper to hold the water in ?

I bought the place a year ago and had a full survey done. This leak was there at the time and the previous owner had done a temporary repair, which after I looked in the attic was pretty obvious and the wood is rotting away. Is there any come back on the surveyor to help cover the cost of the repair ?

Thanks,

don`t presume can you post a picture

Thanks for your response.

I don't have a photo at the moment but some more background. Are you thinking of anything in particular ?

Have looked from the outside with the Binos and no blockage on the gully. I got the surveyor back and he can not figure out why it is leaking. I also had a builder friend look and he can not see any obvious reason, hence the presumption. Lead work looks fine but looks very flat i.e. not much of dip in the gully.

Sounds like there's no lip on the edge side of the lead(?)

Or it seems, not enough lip (unlike my children ). There is a baton running down each side of the gully to raise the sides and form the channel but it doesn't seem very high and the baton on the problem side seems quite close to the main water flow channel.

From the stains and the rotting wood it seems that the water is getting in over this "lip" on the lower section of the gully only, over a 1.5m length.

As there is no apparent damage to the lead I am thinking that the volume of water on this lower length is greater due to the larger area of roof collecting water and the amount of gully above it.

Any other suggestions appreciated as I am no roofer and clutching at straws a little here. I am not yet convinced. Could this be completely wrong and it is e.g. not enough overlap of the slates.

Either way I think I need to get someone up there to replace this section which will require scaffolding and a roofer willing to take on what I guess is a small fiddly job etc. I just want to make sure the problem is solved once the work is done and I have not missed the root cause altogether.

Should be like this as an example,

for some reason, I`m having a job visualising this one

Have you lifted any of the tiles on the leaking side?
The tile should lap over the lead at least as much as the headlap on the tiles and the lead should be folded over on itself at the leading edge.
A photo would help.

Nige F said:

for some reason, I`m having a job visualising this one

Click to expand...

Still got your counting beads

I think there is two difference angle of the roof pitch gulley where it meets up, still need a photo though

moved up to an abacus