One sign not greater than six square feet, including any attachments, shall be permitted on any property, lot or building, advertising the property, lot or building for sale, rent or lease. In the event that more than one realtor is authorized to advertise the property, lot or building, each realtor may place one such sign on the property, lot or building to a maximum of two total signs. Signs advertising that a property, lot or building has been sold, rented or leased shall not be permitted, except in the case of an occupied property, in which case one such sign shall be permitted for a period not to exceed 30 days after closing.