Sealing gap between external walls

[Fresh Cheese]

Next door to my end of terrace two-storey house is a car workshop garage. They have an approx 8' high wall that starts around the middle of my house and stretches back to the end of my garden. This wall runs at a very slight diagonal, starting a few inches out from my wall and then actually joining with mine at the back corner of my house. This means that there is a small gap between their wall and mine. This gap is covered with flashing/guttering that has rotted away, and water appears to be running down into this gap when it rains - this has caused a damp patch on the inside of my wall. The problem is made worse because the garage has a sloping roof that slopes down towards the gap & that has defective additional guttering. The gap is inaccessible from both ends - the only way to get at it is from above (or through the wall I guess).

A diagram might help:

| Roof| Back | |

------|\ |Garage Damp->|| | || | |------| | House |

------| Front

I spoke to the garage owner about this, and he had a friend who is a roofer come take a look at it. He said it would be a difficult job because it would involve removing part of the garage's roof (made of corrugated asbestos-cement sheeting) so that this flashing/guttering could be replaced, and he gave a rough estimate of =A31500 but said that it could be a fair bit more.

I've had two other roofing contractors take a look, and both said they couldn't do anything & the best that I could do would be to inject a chemical DPC in the wall. That sounds like a waste of time to me because it's not tackling the root-cause of the problem. I think the best thing to do would be to clear out any muck that has got into the gap and seal it over.

My questions are:

1=2E Does my solution to the problem of the damp sound like the best course of action?

2=2E Does the garage owner have any responsibility in helping to sort this out? I'm reasonably happy to pay for the work, but I don't really want to have to pay more if the garage owner wants the work to be done outside of their working hours (for example).

3=2E Section 41 of the party wall act (URL below) mentions that there are proprietary products for sealing gaps between walls - anyone know what these are and whether they would be suitable? I couldn't find anything obvious with google. Can anyone recommend a roofer near South Croydon who'd be interested in this job?

House and garage both date from the 1890's (garage was a cow shed back then though!), walls are made of brick.

Thanks for reading - appreciate any help with this.

[Christian McArdle]

1. Does the garage owner have any responsibility in helping to sort this out?

Personally, I would have thought that the garage owner is liable for the damage and should fix his own guttering at his own expense. I might go further and suggest they would be liable for the damp damage to your property, too, although I wouldn't push my luck with this if I wanted to maintain good relations.

You're not allowed to drain your buildings onto your neighbours' walls.

Christian.