I cannot find any direction in the code so it seems to be a grey area. 

I know my target areas and understand zoning/building code to know what I can do. 

Also this should be fairly standard but make sure the electrical is all grounded, I just spent about $5,000 adding outlets and grounding the electrical in a 1950s house to bring it up to today’s code which also meant outlets every six feet instead of one or two in a room.

She told me this ER Doctor had invited guests, the result was that 10 cars were parked on the front yard of my other house, narrowing the street, breaking code and "lowering the value" of her house, two blocks away.  

It also helps if you know how to code instead of just using excel, it saves you a lot of time if you can build models that can predict the cost by drawing live data from the internet.

Union City makes real estate investments almost totally unviable due to ultra strict rent control.

I received an email from an apartment owner saying that he is planning to unload several of his properties in the upcoming months and he plans to take advantage of the 1031 tax code.

At least in NJ all the codes have been digitized. 

@Megan Burns Would this strictly be an investment property or would you be living in one of the units? 

If this is a duplex hooked up to septic (like some of the older, converted homes in Indy and more rural areas for example) you would need tp verify that your local code supports this conversion of useable square footage as supported by the current septic tank size or install a larger/additional tank.