Contact the county tax collector & state revenue department.

One city department originally told me "no way, no how" would this ever be approved.

Hi Seth,Yup, that's an important distinction that Fannie makes when doing owner occupied v non owner occupied math.If you're buying another primary residence, then that new home will have the owner occ math, and the departing primary residence non owner occ math.It also may be a non-issue.

I believe I found the city's info site:https://www.stlouis-mo.gov/government/departments/...According to that link, there were about 600 properties available at the 13-june auction.

I am not very experienced with this sort of thing, but I like the idea of hiring a home inspector or an Architect to walk through the home with you to give you an idea of what violations exist and the estimated cost of becoming compliant.I would definitely stay away from asking the City building permit department, etc.  

Policy rates have to be filed by the company with the State Insurance department in that state.  

Also call the Building Department and explain your situation.

If you'd like more in-depth knowledge, you can read the link at the end from the EPA.I would start by going to your State Department of Environmental Management.

Make sure before you do anything you talk to the county/city building department and make sure they will allow a secondary dwelling on your property if you haven't already :) Also it does make a difference if the secondary dwelling will be attached or detached to the main house for loan possibilities and permits. if you need a lender...let me know and I'll put you in contact with my guy whom I quoted above. 

I am well aware of zoning and I plan to check with the city's building department.