Thank you so much for sharing your knowledge and experience.Found a lot of good resources (such as 'Handyman Matters') for handling my real estate investments. 

I basically figured I could reduce my dad's rent (he pays 45% less) and pay the overwhelming majority of the costs by renting out the other unit.

I can handle everything from purchase to stabilization and management.

How would i handle this situation.

If it's still damp now, rent a couple of commercial fans and dehumidifiers to reduce the humidity. 

Plus, this cycle is likely nearing a peak - it can't keep going like this forever and interest rates can really only go up in the near future, reducing people's buying power.

It can be handled through a realtor.

If someone has gone through this and could share how they handled it, I would appreciate any tips.

We are a full service management company and currently vendor out all day-to-day maintenance to a small contractor who handles the majority of our maintenance full time (3 maintenance techs). 

They normally just have a tax preparer (which is basically just inputing the information). 85% of accountants just prepare taxes and don't actually find unique loop holes and ways to reduce the investors taxable income.