Boarding house idea from "Aggressive Retirement" Podcast?

[Steve Arnold]

I heard a BP podcast recently with Rachel Richards as the guest. She mentioned that she had bought a house and converted it into a boarding house type arrangement. She rented the bedrooms, and tenants had access to the common areas. She said the cashflow was really strong using this approach.

Anyone here try that? Is it as simple as just buying a 3BR house, and renting to 3 separate tenants? Are there laws limiting this? 

Interested in your thoughts.

-Steve