Rising home prices for developers isn't new, but if you were in contract, what they did is most likely illegal.

Egress: Two methods of egress, typically a door and a window.Ceiling height: At least half of the room should have a ceiling height of 7 feet.

What screens do you do, or not do?

I don't know if this is a recent trend that's come about with the rise in popularity of laundromats, but I've noticed more "fix & flip" situations on the market - mats being sold by owners who have owned for 1-3 years and put some significant improvements in.

Think about it like this - the customer pays for all the doors and windows, for let's say $30,000.

It is usually much easier to seal a existing door way then it is to move walls in my experience. 

I personally started investing there in 2019 with a budget not too far off from yours, and I've been able to build up a portfolio of 12 doors since then, which now kicks off over $16,500 in gross monthly rents.Detroit has a lot going for it—affordable price points, strong rental demand, and good opportunities for cash flow, especially with single-family homes and duplexes in certain areas.

There can also be chemicals in the treated lumber that are harmful to the environment.Invest in a good screen or built in door system.  

We also own the building next door so idea would be to relocate the tenants to that building after building it out.  

Assuming you have another stream of income when you move there and I hope you do, I would recommend using the smallest amount of capital possible and invest in the most doors (1-4 units) that you can.