Artikel 66

(1) Stairways which penetrate only a single deck shall be protected at least at one level by at least “B-O” Class divisions and self-closing doors. Lifts which penetrate only a single deck shall be enclosed by “A-O” Class divisions with steel doors at both levels. Stairways and lift trunks which penetrate more than a single deck shall be enclosed by at least “A-O” Class divisions and protected by self-closing doors at all levels.
(2) All stairways shall be of steel frame construction except where the Administration permits the use of other equivalent material.