3 flat plus coach house in Chicago

[Joy Williams]

Has anyone bought a 3 flat + coach house in Chicago recently? I'm interested in one where the 3flat is in pretty good condition but the coach house is a mess and needs a complete gut. It's an REO. My potential lender indicated that the coach house is probably grandfathered in but to do an FHA loan with a 203k they would need a "rebuild letter" which could take 3-6 months to get. I wouldn't add any square footage though I may want to use part of the space as a one car garage since the house is two stories. Could the appraiser's assessment stand in lieu of the rebuild letter? It sounds like I may need to get an architect involved and deal with zoning. I'm not sure though. I'm trying to think through all of this before offering. Thanks in advance for any advice you can provide!