§ 280. Water-closets and bathrooms. The requirements for water-closet compartments, bath and shower rooms shall be the same as provided in section two hundred fifteen for fireproof dwellings, except that each required water-closet compartment, bath or shower room in an apartment shall be ventilated by a window opening to the outer air as provided in section one hundred seventy-one. Water-closet compartments, bath and shower rooms which are supplementary to those required under the provisions of sections one hundred seventy-one and two hundred fifteen may be mechanically or gravity ventilated as provided in section one hundred seventy-one.