Even if you rent it for less, it will save you a lot.For example, a simple ADA bathroom will easily cost $ 6-7,500.  

You will get all manner of quotes, depending on materials and other factors- will you have xray machines, do you need center run power /water (i.e. dentist office) or do you do day surgery (will require automated backup generators IIRC), are your clients physically disabled, do you need chair lift, if you change an old building do you have to make it ADA compliant. 

-HAZMAT mitigation-Additional plumbing installed and water consumption (commercial building usually has fewer bathrooms)-Neighbor protests to your re-development idea-Bringing an old commercial building up to modern residential codes (fire/ADA/safety/etc)-Are any amenities close by (industrial neighborhoods don't always have a supermarket or restaurants near by)?

Our last commercial project was originally not in current ADA compliance when built (early 80's), and due to the extent of the renovations the county required us to bring the building into compliance, which was lots of $$$$$.

We told her that she is allowed under ADA and Airbnb guidelines to bring a dog as long as the animal is not out of control, never left alone at the property, and that it must be housebroken (copied and pasted from Airbnb's website). 

You use the existing ad as the control and then try an alternative.

The lower unit is ADA equipped for a wheelchair user, and will require about 5-7K in repairs to convert it back to a non-disabled use apartment. 

It would be so great if landlords on BP could make a modicum of effort to understand the HUD, FHA and ADA rules.  

I'm going to say the addition of the 5th unit will kill the cash flow because of the increase in cost to a commercial loan and all of the renovations (ADA compliance, sprinklers etc...). 

@Jeff Rabinowitz :-) Just posted the ad as written.