I think it really helps build rapport and cement a positive relationship.

My contractor is urging me just to get a dehumidifier in the basement, open up these cemented in windows in basement for some air flow and put bleach on walls for mold but we didn’t discuss the foundation.Would appreciate some advice.Thanks and happy holidays!

There is also a stair case crack on the brick exterior(no interior cracking).

I would either stair step them up or keep rents the same for a few months if they agree to move out.

Here are general details:-1st floor needs to accommodate approximate 55 parking stall for the 36 units-Parking will take up around 20,000sf of space-The remaining square footage of about 4,000sf can house elevator lobby, stairs, trash, electrical transform, commercial space etc.-36 allowed units at 850sf average size require about 30,000sf of building. adding the circulation and non-residential square footage pushes this number up to a total building of about 40,000sf.

However, the sewer is 12 feet deep, runs underneath a set of concrete stairs and then 25 feet into a main city arterial. 

Built on a cement slab, and still had to be lifted.

Making the basement a legal ADU would require removing the concrete and digging the floor down some to get to legal ceiling height, Another option would be to make the basement legal living space with less stringent permitting requirements by legalizing the old basement stairs -- not sure how much that would cost -- guessing 10-15K.

The Setup is like this.3rd: BR/BR2nd: BR/BR/BR/Bath1st: BathSo the first floor bath is kind of awkward for the third floor tenants to walk down 2 flights of stairs to shower. 

Could also just be a tenant dispute but need to know more about the situation, possibly asking the up stairs tenants to sit down and speak about the issue and what the following course of actions will be if this continues.