QuoteYou knew about the leak for 12 months and did nothing. If it was your responsibility to fix it or your responsibility to tell someone else to fix it then not doing so could be considered an act of negligence.
Ok so about 12 months ago I had a leak in my bathroom. It was a small leak due to a faulty seal in one of the pipes.
QuoteYour leak caused the damage and if your are responsible for fixing the leak then you are also responsible for repairing the damage. If your insurance covers it then by all means turn in a claim. The other guy's insurance is likely not obligated to pay for damages caused by third parties. Even if they were, they would still have a cause of action against the thrid party who caused the damage.
Surely it's just a matter for the insurance and I couldn't be personally liable for the damage.
QuoteThis is about the only thing going in your favor. The damage to the downstairs apartment didn't occur instantly; it occurred gradually over a period of time. You had no way of knowing that damage was occurring in that apartment but it's occupant did know. He could have informed you much earlier in the process but choose not to. If he had informed you when the damage first started to occur there would have been much less damage.
When the guy downstairs told me about the leak, I immediately turned off the water and then isolated the problem and stopped the leak more or less immediately so I wasn't negligent in repairing the leak.
A case could be made that you should only be liable for a portion of the damages.
All of the above is of course highly dependent on the specific laws in your jurisdiction, the terms of the rental/lease contract, and even the political fashion of the day. Unfortunately you will have to hire an attorney to find out wassup, Bear in mind that plasterers are usually much less expensive than lawyers. Good luck!