National Building Code of the Philippines

(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) Landing . 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 newel 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. (10a) Stairways Construction-Interior . Interior stairways shall be constructed as specified in this Code.  Where there is enclosed usable space under the stairs the walls and soffits of the enclosed space shall be protected on the enclosed side asrequired for one hour fire resistive construction. (10b) Stairway 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.