The city of Boulder has specific laws when it comes to how many unrelated people can live in a rental dwelling. Maximum occupancy is determined by zoning district. Property owners, managers and tenants are responsible for knowing the allowed legal occupancy. Advertisements for rental units also must state the maximum number of unrelated occupants. There are fines for violations of the code.
Every operator of any property with fewer than five dwelling units, shall at the time any dwelling unit is shown to any prospective renter, post conspicuously on the inside of the main entrance to each dwelling unit a sign listing a maximum occupancy number that shall be no greater than the maximum number of unrelated individuals permitted.