In my duplex, I have an electric heater installed on the wall in the back stairwell.

If the latter, and it is a common roof, over some shared walls, what happens when your neighbor doesn't have the money to keep their roof in good condition, and the leaks work their way to your property.  

Also want to do something instead of the tile on the walls.

Thank you.There's reaching out to an Interior Designer but they may be limited since they may be unfamiliar with moving of walls especially if load bearing.

I hate having to re-paint every few years.Similar to @Jaron Walling, I look for properties with slab/foundation problems.....

Quote from @Jaron Walling: @Nimit A.

Our duplexes come with R20 ceilings and R14 exterior walls this provides a level of insulation much higher than is standard and results in lower energy costs and is an element that can be taken into consideration in appraisal-Seek home improvements above stock plan to close the deal with your modular dealer.

We filed a claim immediately but was denied because the water damage stemmed from "shallow groundwater" infiltrating the slab then walls.

@Gene Jung you have  a few basic options:1) Invest in a REIT: hands off, but subject to the whims of Wall Street2) Invest in a syndication: hands off, but you must do a lot of research on the managing member.3) Invest in Notes or Private Lend: not passive and you will need to educate yourself on market and legalities.4) Invest in Mutli-family apartments: not passive and you will need a good PMC you can trust5) Invest in SFR: not passive and you will need a good PMC you can trust

Your PM fees will also be less per unit for a multi unit vs single family.Tenants in multi unit buildings share walls so there is always the potential for noise complaints and neighbors that simply can't get along with each other.If you run into financial difficulties, it is much easier to sell off one or two SFRs than it is to sell one big multi unit.Traditional lending is much easier right now for SFRs vs multi units.