§ 296. Laundries. A shop, room or building where one or more persons are employed in doing public laundry work by way of trade or for purposes of gain is a factory within the meaning of this chapter and subject to the provisions relating to factories. No such public laundry work shall be done in a room used for sleeping or living purposes. All such laundries shall be kept in a clean condition and free from vermin and from all impurities of an infectious or contagious nature. This section shall not apply to a female doing custom laundry work at her home for regular family trade.