real estate laws?

I have a three story building here in Dallas, GA. We live on the second floor that I converted into a home for my family. It has two bedrooms and two bathrooms. The third floor is now a space for transient boarders where they can rent the place for a short time. Recently, my wife and I decided to have a laundry business on the first floor of the building. However, a friend of mine says that it would be illegal to do so? Why? How can that be illegal? It is my own building. He said I should consult a lawyer about the cities real estate laws. Is he right about it? Should I follow his advice?

imo, it is better to consult first a lawyer/agent about that just to be safe..
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Real Estate