§ 268. Exterior screened stairway. "Exterior screened stairway" means
a stairway conforming to the following requirements:

1. It shall be built of incombustible material.

2. The risers of the stairs shall not be more than seven and
three-quarters inches in height and the treads not less than ten inches
wide.

3. On each floor there shall be a balcony connecting with the stairs.

4. Access to the balconies shall be by means of fire doors extending
to the floor level and which shall slide freely or open outwardly so as
not to obstruct the passageway.

5. All windows or other openings upon the course of such stairs shall
be fireproof.

6. The level of the balcony floor shall not be more than seven inches
below the level of the door sill.

7. The stairs shall continue from the roof to the ground level and
shall lead (a) directly to a street, or (b) to a fireproof enclosed
passageway independent of other exit from the building and leading to a
street or road, or (c) to an open area having communication with a
street or road.

8. The balconies and stairs shall be guarded on the sides by a screen
of incombustible material.