Looking for ballpark costs on Chicago duplex-up gut rehab

[Andrew Simpson]

My wife and I bought a two-flat in the Avondale neighborhood a few years ago. It's a pretty typical framed Chicago multi-family, complete with in-law units in both the basement and attic. Currently, we're living in the first floor unit and rent out the second floor and attic. Our current unit is nice, but just too small for us at ~950 sq ft with both of us working remotely. Eventually we'd like to duplex-up the second floor unit into the attic for ourselves (then rent out the first floor unit).

It would definitely be a big job, as we would be looking to add dormers to increase useable sq footage in the attic. Attic would be a full gut with the dormer additions to create a new layout with additional bedrooms and bathroom(s). Second floor unit would need at least partial rehab (or potential full gut to re-layout if it makes more sense to make better use of the space), kitchen would definitely be fully rehabbed. With the dormers, it would also need almost a whole new roof as well (was thinking of standing seamed steel to just one and done it). 

We are aggressively saving cash for this, and hope to be able to do the whole job with little or no need for a loan. Hope to be there in 2-3 years. My initial gut estimates are $120-150k, is this in the general ballpark for a multi-scope project like this? Also open to having a call with a GC to talk it out if any has one they'd recommend for large projects like this. 

Had also considered a duplex down, but the basement ceilings are only 6'4", which would require a dig down, which brings in a whole host of other issues like having to have escape windows below grade for code, and all the attendant drainage issues that would come along with that.