DUNA VISTA 2020 1007.8-1009.1.1
1007.8 Special stairs 2. The height of risers shall not be more than 91/2
1007.8.1 Winders shall have a minimum tread depth of 6 inches(241 mm).
inches(152 mm)at the narrow edge and shall have a min- 3. The headroom shall be a minimum of 6 ft 6 in.
imurn tread depth of I I inches (279 mm) at a point 12 (1981 mm).
inches(305 mm) from the narrow edge.Winders shall be 4. Treads shall have a depth not less than 71/2 in.
permitted to be used as a component in the means of (190 mm)at a point 12 inches(305 mm)from the
egress within a dwelling unit. narrow edge.
5. All treads shall be identical.
1007.8.2 Spiral Stairways. Where permitted by this sec- 6. Handrails shall be provided on one side.
tion or in specific occupancies in accordance with 1018,
spiral stairs complying with this section shall be permitted 1007.8.3 Circular stairways shall be permitted to be used
as a component in a means of egress. as a component in the means of egress providing the min-
1007.8.2.1 Spiral stairs complying with the following imum.depth of tread is not less than I I inches (279 mm)
shall be permitted: measured 12 inches (305 mm) from the smaller radius,
I. Riser heights shall not exceed 7 in. (17.8 cm). and the smaller radius is not less than twice the width of
2. The stairway shall have a tread depth of not less the stairway. In Group R3 Occupancies, circular stairs
than I I in.(27.9 cm)for a portion of the stairway may have a minimum tread depth of 9 inches (229 mm)
width sufficient to provide the egress capacity for with I inch (25.4 mm) of nosing, and the smaller radius
the occupant load served in accordance with may be less than twice the width of the stairway.
1003.1.
3. At the outer side of the stairway, an additional 1007.8.4 Alternating tread stairways shall have a mini-
10-1/2 in. (26.7 cm) of width shall be provided mum projected tread exclusive of nosing of 81/2 inches
clear to the other handrail, and this width shall (216 mm) within a minimum total tread depth Of 101/2
not be included as part of the required egress inches(267 mm).The rise to the next alternating tread stir-
capacity. face shall be a maximum of 8 inches(203 mm). Distance
4. Handrails complying with 1007.5 shall be pro- between handrails shall be a minimum of 17 inches (432
vided on both sides of the spiral stairway. mm)and a maximum of 24 inches(610 mm).A minimum
5. The inner handrail shall be located within 24 in. distance of 6 inches(152 mm)shall be provided between
(61 cm), measured horizontally, of the point the stair handrail and any other object.A minimum of 12
where a tread depth not less than I I in.(27.9 cm) inches (305 mm) shall be provided between the stair
is provided. handrails of adjacent alternating tread stairways.
6. The turn of the stairway shall be such that
descending users have the outer handrail at their 1007.8.5 Alternating tread stairways meeting the require-
right side. ments of 1007.8.4 shall be permitted to be used as a com-
ponent in a means of egress from a mezzanine of not more
1007.8.2.2 Where the occupant load served does not than 250 sq ft (23 M2) in area serving not more than 3
exceed three and from mezzanines not exceeding 2-50 occupants in F,H. I, within dwelling units of R2 and R3
sq ft.(23 m2)and an occupant load of three or less,spi- and S occupancies.
ral stairs meeting the following conditions shall be per-
mitted. SECTION 1008
1. The clear width of(lie stairs shall be not less than ACCESS TO ROOF
26 in. (66 cm).
2. The height of the risers shall not exceed 9 112 in. Buildings four stories or more in height, except those with a
(24.1 cm). roof slope greater than 4:12.shall be provided with a stairway
3. Headroom shall be not less than 6 ft 6 in. (198 to the roof. Such stairway shall be marked at street and floor
cm). levels with a sign indicating that it continues to the roof.Where
4. Treads shall have a depth not less than 71/2 in. roofs arc used for roof gardens or for other purposes,stairways
(19.1 cm) at a point 12 in. (30.5 cm) from the shall be provided as required for such use or occupancy.
narrower edge.
5. All treads shall be identical. SECTION 1009
6. Handrails complying with 1007.5 shall be pro- HORIZONTAL EXITS
vided on both sides of the spiral stairway.
1009.1 General
1007.8.2.3 Within dwellings and dwelling units, guest 1009.1.1 Horizontal exits shall not comprise more than of
rooms and guest suites where the occupant load served the required exits from any building or floor area and shall not
does not exceed five,spiral stairs meeting the following serve as the only exit.The walls of horizontal exits shall have
conditions shall be permitted: a tire resistance rating of 2 hour-,using materials dependent on
1. The minimum stairway width shall be 26 inches the type of construction.
(660 mm).