Need legal advice as for a general contractor job? -

I did a job for a client, sealing a roof of a storage place. Although I sealed it all , the water leaked somehow and the client says it is my fault. Around the roof there are kind of walls , which is all rotten, and I know the leak is from the walls down tot he floor. The walls were not part of my job, I have not sealed them , and they are all rotten. I did just the roof.I did not have any signed contract with him , did not give him any warranty. I know it is from the walls, I sealed it all properly and the walls need to be redone. It is a wood walls around it. But he says it is my responsibility.Can he sue me for that? If I have nothing in writing or warranty can he still do something?Thanks.

He can sue the question is can he win. My guess is that without a written contract specifying exactly what you were doing and what your liability was he stands a good chance of winning. I know of a similar case where the contractor claimed he was hired to do one thing and the homeowner sued for damages due to something else. The customer claimed he hired the contractor to fix some leaks and the house still leaked when the contractor finished. The homeowner said he didn t have the expertise to know where the leak was coming from. If the house needed other repairs the contractor should have told him what needed to be done before starting the job. The judge ruled in the homeowners favor. The contractor did get paid for most of the work that was done because there was no dispute that the work was done properly.