Illegal Unit In Apartment Building

[The Warrior Monk]

I quickly glanced through this thread and generally agree with Denis and gobears. The only thing I would add is that there is much more involved that a use being "permitted by zoning." There are also health department regulations (e.g., sewage disposal, etc.), parking issues, etc. to be dealt with. If an additional unit is not allowed in the first place and adds to the burden of a public sewage disposal system, or exceeds the sanitary flow of the property is a public system doesn't exist, that is going to typically be treated differently than if someone has an unpermitted deck.