Structural problems in an attached rowhouse..need opinions
I recently purchased a victorian rowhouse that is the end unit of a 3 unit structure. All 3 The properties were converted into duplexes in the early 80's and this past week we started renovations on our duplex unit to turn it back into a SFH.
We have discovered some big structural problems. The largest problem is that our back exterior wall failed or has sunk and caused internal damage. Our contractor is guessing that it has settled, and the current damage is the extent of the damage we will have.
Yesterday the wall to wall carpeting and plywood was pulled up on both floors in the back of the building and we discovered that a previous owner had floated the plywood in parts to give the illusion of a level floor when in reality the real wood floors had to be cut in a straight line to allow the wood to sink with the exterior wall. The floors are dipping a few inches towards the back of the house. Essentially a marble would roll towards the rear of the house if placed in either of the 2 back rooms. (picture below)
My contractor said the exterior wall is failing and he is concerned because if he lifts the rear of the house he is likely to effect the floors and walls in the other connected unit next door.
When construction started I talked with the owner of the other 2 units about a potential electricity issue and he has been very nice. His 2 units are rentals and we were joking back and forth about 'handyman special' type of things we have found in our respective units. (he purchased his 2 units about the same time we purchased our unit. Previously all 3 units belonged to one owner.)
When we removed the baseboard from the connecting wall we could see there is plywood on top of the floors in the unit next door to us. They most likely have the same issue we have. But the unit is occupied by tenants and the owner is not interested in doing much aside from collecting rent. He's not going to want to participate in any fix up that will disrupt the tenant or cost him more money than the rental is worth to him.
My contractor has suggested supporting the unit next door underneath with joists or beams or something and then "cutting our unit loose" by cutting the underneath beams connecting my unit to the one next door. This way he can lift my unit and do whatever support is necessary to fix my exterior wall and floors without causing damage to the unit next door. He's going to have 2 other contractors come out next week to look at the issue so they can create a plan.
The contractor says that this plan will not damage their roof or fireplace which is still going to be connected to our unit.
My question is what do I disclose to the owner of the other units? Our units are connected. This must come up at least sometimes. I am partial to telling the owner everything we have found and being very transparent regarding what our plans are to fix my unit. I'm just afraid he's going to use our renovation as a cause for any damage he finds in his units in the future. His units are both just as f-ed up as ours is- but its not so apparent until you actually expose walls and floors that you can start seeing the cause of the damage.
What if I tell him everything we are doing and then in a year he sues me or expects me to start paying for fixes on his units saying my construction caused the damage he has on his units?