I would start by hiring either a local real estate attorney or local engineer or architect who regularly navigates these waters.

For our highest risk deal, a SFH on land zoned for 10 units, we developed a concept design with an architect and complete a pre-app meeting with the city all prior to closing.

However, after some research and a little back and forth with the architect we were able to find out that Philadelphia has some exemptions for sprinkler systems/permits.

Here in NYC, which I consider to be a pretty tough environment, the Architects we work with consistently approve deposits of 25% to 30%.

--I am a former architect, but then was a stay-at-home mom for the last 20 years (I've done a lot of small jobs on the side for myself and friends, but I only know how to hand-draft; now-a-days you need to be proficient in two or three CAD programs to get a job in an architecture firm!)

The architect should be ashamed.

I would get in contact with an architect and/or a local city or county building inspector whichever hold jurisdiction in that locale off the record. 

(Get yourself a laser measure, I have a Bosch, was about $70)Here is a little background: the majority of Milwaukee houses have been built in the 1920 and in the 1960s, so plans were either prints (for the common folk) or hand drawn by an architect (for the wealthy). 

Wow, your son is designing the building, you have a son old enough to be an architect?

He also has construction experience and is currently an architect.