Question - Converting a basement to a bedroom??

[Vincent DeAngelis]

I know it's possible to convert a basement into a bedroom, but I've heard that it can be difficult.  I know that the requirements also differ based on location you're looking to purchase a property.  Is there a website (or place I can be directed), where I can specifically look up my location and the laws/guidelines that dictate bedroom requirements?  

There is a duplex that I'm hopefully looking to get under contract, but one of the "make it or break it" value adds that would make this property a good (or great) investment, is this conversion.  

Any help would be appreciated.  Thank you!