garage roof leak damaging neighbours side

[silverfoxcc]

Neighbour and i share a garage block,sort of semi detached with common dividing wall., with a corrugated asbestos roof.There are three cross beams running between the outside walls to screw the asbestos panels to.
My side, for many years following rain, has drips running the length of the garage corresponding with the dips in the roofing. I always thought is was getting in where the roof panels overlap. And several times i have put a sealanton the roof at the join to stop it, it is on average about every 3-4 years. Previous neighbours have never mentioned this at all.
New neighbour then got his roof converted to a flat type , leaving mine as original.
Now he is getting water ingress damaging his false ceiling.following heavy rain
Got his builder to look today whilst it was raining and he noticed the the water is coming from where the roofing on my side has lost its sealing capability where it is attached to the cross beams and is running along the beam, through the connecting wall and causing the problem.
He did suggest that my side be treated with a overall sealant that would stop the leakage.and the neighbours roof be repaired/replace
No doubt this can be covered by insurance, for his damage, and i would expect that his company will find i am liable...no problem with that. Would my insurance also cover the repair to my roof?
Ironically this moring got a circular adverting leaky roof repairs.
Oh as it looks like i am left with the costs of getting my roof sealed,any ball park guestimates out there. Didnt want to be seen as keen to want to dip into my pocket at this stage. Get on great with them so want to keep it as amiable as possible

Edited by silverfoxcc on Thursday 22 January 22:54

[NumBMW]

I wouldn’t bother with those little oak stands to keep the cables off the floor. There’s a whole thread on that scene!