Concerns regarding an unpermitted addition

[Farrol T.]

Good morning all! I'm a newbie looking to rehab what was my primary residence to get it rent ready and I'd like some input from you seasoned professionals.

The house has a full, first floor rear addition built by the PO that includes an eat-in kitchen, master bath, and walk-in closet, but was never permitted. Signs that things were askew included 4" wall tiles on the bathroom floor, no GFCI outlets, and ceramic tile over plywood in the kitchen. I just had a roofer check a leak back there and the roof doesn't have the proper pitch to drain water...it's essentially flat and the house is a Cape Cod so water has made a mess of things over the years. He recommends tearing it out and replacing with a rubber roof for about $1250. I only have about $18K available for the whole thing (drywall 2 upstairs bedrooms, new kitchen, siding, deck repair/replacement, and this roof are the known majors at this point)...is this even feasible at my price point? Furthermore, what would have to be done to "redeem" an unpermitted structure on a house? The house now has additional sq footage and a full bath that are not on reflected in public records.

I don't want to put a band-aid on a gunshot wound, but any and everything could be wrong with this addition and the unknown has me paralyzed at this point. Also, the PM I'll be contracting with has offered some assistance in this area, but I'm sure it'll be at a premium...I just want the jobs done well for a fair price. To that end, I plan on contacting a REIA in the area (house is in MD, but I'm in FL) to get some references for rehab contractors that can work with me quickly and efficiently without costing me an arm and a leg! Thanks in advance for the feedback!