Houses with "Extra" Areas

[Trevor J Dammon]

Hey all,

I'm new to the real estate journey and have starting running numbers on duplex/triplex/quadplex in the Minneapolis area. Occasionally I see a description on the MLS that says something like 3rd floor/basement/extra area that could be turned into an additional unit.

For example: https://www.zillow.com/homedet... "Large versatile 3rd level could be 4th bedroom, owners suite, office or 3rd living area."

What sort of things should I be looking for or asking the realtor when analyzing a property with this "extra space".  If anyone has successfully added an extra unit to a property like this I'd love to hear your story!  

Thanks all.