Rooms in which articles are hung up to dry after cleaning shall be separated from dry cleaning rooms by partitions having a fire-resistance rating of not less than two hours if Class II system solvents are used, and not less than one hour if Class III system solvents are used. Entrances to dry rooms shall be provided with approved, self-closing fire doors. Ventilation of drying rooms shall conform to the requirements for ventilation of dry cleaning rooms and the provisions for fire extinguishing equipment shall be complied with. If the drying room is in a separate building, it shall conform in construction and equipment to all requirements for dry cleaning buildings.