I have two, single floor duplexes that are on an alley.

We have a duplex and will STR the first floor while we live on the second. 

@Tony Sherman, yes.Closing delays on buy side with title issuesMaterial delays, which can compound into contractor delays when you try to keep schedules tightContractor delays because prior jobs are not wrapping on timeContractor delays because you need to fire one and hire a new oneScope of work issues, i.e. no signs of moisture intrusion prior to buying, but all of a sudden you have a wet floor after a good hard rain.Closing issues on sale sideHow do you manage?  

The fourth thing they have is engineered hardwood flooring.

Keep in mind the foundation is not the only issue, when there is foundation issues there is usually other internal issues that go along with it, (wall separation, Possible broken pipes, floors etc) so give yourself plenty of wiggle room for repairs.

As far as ROI, there are a few givens that will always give the majority or even dollar for dollar back, such as landscaping, flooring, updated kitchen and bathrooms, and security systems.

There is a high cost to renovating a non-restaurant space into a kitchen, especially if you need everything like grills, hood vents, walk-in coolers and grease traps in floors, not to mention the utilities to service all of the above.

However, if you are doing cosmetic renovations (paint, floors, countertops, etc) you do not need any forms...just keep track of your spend to share with your tax guy at the end of the year. 

The building has two units per floor with the top floor vacant.

Most basements get water in them at some point in my experience and I see “inadequate drainage”, “negative grading”, “recommend extending downspouts” etc. on most inspection reports.We had a property with a humid crawl space basement and set up a dehumidifier with a hose coming from it to a floor drain so that we didn’t have to keep emptying it’s tank all the time.