Article 122Supplement v1, p. 122

COMMERCIAL LAWS SUPPLEMENT

stairway where the treads are narrower but in no case

shall any width of run be less than 150 millimeters at any

point.

(4) Circular Stairways . — Circular stairs may be used as an

exit provided the minimum width of run is not less than

250 millimeters. All treads in any one flight between

landings

shall have identical dimensions within a 5

millimeter tolerance.

(5) Landings . — Every landing shall have a dimension

measured in the direction of travel equal to the width of

the

stairway. Such dimension need not exceed 1.20

meters when the stairs has a straight run. Landings when

provided shall not be reduced in width by more than 100

millimeters by a door when fully open.

(6)

Basement Stairways . — Where a basement stairway

and a stairway to an upper storey terminate in the same

exit enclosure, an approved barrier shall be provided to

prevent persons from continuing on to the basements.

Directional exit signs shall be provided as specified in this

Code.

(7) Distance Between Landings . — There shall be not

more

than

3.60

meters

vertical

distance

between

landings.

(8) Handrails . — Stairways shall have handrails on each

side and every stairway required to be more than 3.00

meters in width shall be provided with not less than one

intermediate handrail for each 3.00 meters of required

width.

Intermediate

handrail

shall

be

spaced

approximately

equal

within

the entire width of the

stairway. Handrails shall be placed not less than 800

millimeters nor more than 900 millimeters above the

nosing of treads and ends of handrails shall be returned

or shall terminate in nowel posts or safety terminals:

Except , in the following cases: Stairways 1.10 meters or less

in width and stairway serving one individual dwelling unit

in Group A or B Occupancies may have one handrail,

except that such stairway open on one or both sides shall

have handrails provided on the open side or sides: or

stairway having less than four risers need not have

handrails.

(9) Exterior Stairway Protection . — All openings in the

exterior wall below or within 3.00 meters, measured

horizontally of an exterior exit stairway serving a building

over two storeys in height shall be protected by a

self-closing fire assembly having a three-fourths hour

fire-resistive

rating:

Except, that

opening

may

be

unprotected when two separated exterior stairways serve

an exterior exit balcony.

(10) S tairway Construction-Exterior . — Exterior stairway

shall be of incombustible material: Except, that on Type III

buildings which do not exceed two storeys in height,

which are located in less fire-restrictive Fire Zones, as well

as on Type I buildings may be of wood not less than 50

millimeters in nominal thickness. Exterior stairs shall be

protected as required for exterior walls due to location on

property as specified in this Code. Exterior stairways shall

not project into an area where openings are required to

be protected. Where there is enclosed usable space

under stairs, the walls and soffits of the enclosed space

shall be protected on the enclosed side as required for

one-hour fire-resistive construction.

(11) Stairway to Roof . — In every building four or more

storeys in height, one stairway shall extend to the roof

unless the roof has C slope greater than 1 in 3.

(12) Headroom . — Every required stairway shall have a

headroom clearance of not less than 2.00 meters. Such

clearance shall be established by measuring vertically

from a plane parallel and tangent to the stairway tread

nosing to the soffit above all points.

(f) Ramps . — A ramp conforming to the provisions of this

Code may be used as an exit. The width of ramps shall be

as required for corridors.

(g) Horizontal Exit . — If conforming to the provisions of

this Code, a horizontal exit may be considered as the

required exit. All openings in a separation wall shall be

protected by a fire assembly having a fire-resistive rating

not less than the occupant load served by such exit. The

capacity shall be determined by allowing 0.30 square

meter of net floor area per ambulatory occupant and 1.90

square

meters

per

non-ambulatory

occupant.

The

dispersal area into which the horizontal exit loads shall be

provided with exits as required by this Code.

(h)

Exit Enclosures . — Every interior stairway, ramp, or

escalator shall be enclosed as specified in this Code:

Except, that in other than Group D Occupancies, as an

enclosure will not be required for stairway, ramp, or

escalator

serving

only

one

adjacent

floor

and

not

connected with corridors or stairways serving other floors.

Stairs in Group A Occupancies need not be enclosed.

(1)

Enclosure

walls

shall not be less than two-hour

fire-resistive construction. There shall be no openings into

exit enclosures except exit doorways and openings in

exterior walls. All exit doors in an exit enclosure shall be

appropriately protected.

(2) Stairway and ramp enclosures shall include landings

and parts of floors connecting stairway flights and shall

include a corridor on the ground floor leading from the

stairway to the exterior of the building. Enclosed corridors

of

passageways

are

not

required

from

unenclosed

stairways.

(3) A stairway in an exit enclosure shall not continue

below the grade level exit unless an approved barrier is

provided at the ground floor level to prevent persons

from accidentally continuing into the basement.

(4)

There shall be no enclosed usable space under

stairways in an exit enclosure, nor shall the open space

under such stairways be used for any purpose.

(i) Smokeproof Enclosures — A smokeproof enclosure

shall consist of a vestibule and a continuous stairway

enclosed from the highest point to the lowest point by

walls of two-hour fire-resistive construction. In building

five storeys or more height, one of the required exits shall

be a smokeproof enclosure.

(1)

Stairs

in

smokeproof

enclosures

shall

be

of

incombustible construction.

(2) There shall be no openings in smokeproof enclosures,

except exit doorways and openings in exterior walls. There

shall be no openings directly into the interior of the

building. Access shall be through a vestibule with one

wall at least fifty percent open to the exterior and having

an exit door from the interior of the building and exit

door leading to the smokeproof enclosure. In lieu of a

vestibule, access may be by way of an open exterior

balcony of incombustible materials.

(3) The opening from the building to the vestibule or

balcony

shall

be

protected

with

a

self-closing

fire

assembly

having

one-hour

fire-resistive

rating.

The

opening from the vestibule or balcony to the stair tower

shall be protected by a self-closing fire assembly having a

one-hour fire-resistive rating.

(4) A smokeproof enclosure shall exit into a public way or

into an exit passageway leading to a public way. The exit

passageway shall be without other openings and shall

have walls, floors, and ceilings of two-hour fire-resistance.

(5)

A

stairway

in

a smokeproof enclosure shall not

continue below the grade level exit unless an approved

barrier is provided at a ground floor level to prevent

persons from accidentally walking into the basement.

(j) Exit Outlets, Courts, and Passageways — Every exit

shall discharge into a public way, exit court, or exit

passageway. Every exit court shall discharge into a public

way or an exit passageway. Passageways shall be without

openings other than required exits and shall have walls,

floors, and ceilings of the same period of fire-resistance as

the walls, floors and ceilings of the building but shall not

be less than one-hour fire-resistive construction.

(1) Width — Every exit court and exit passageway shall be

at least as wide as the required total width of the tributary

exits, such required width being based on the occupant

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