20 important limitations of Stairways as per NBC code
We have shared the important limitations for stairways as per National Building code.
a) Interior stairs shall be constructed of non-combustible material throughout.
b) Interior stairs shall be constructed as a self-contained unit with at least one side adjacent to an external wall and shall be completely enclosed.
c) A staircase shall not be arranged round a lift shaft for buildings 15.0 m. and above height. The staircase location shall be to the satisfaction of Chief Fire Officer.
d) Hollow combustible construction shall not be permitted.
e) The minimum width of internal staircase shall be as given in bye-law 4.8.6.
f) The minimum width of treads without nosing shall be 25 cm. for an internal staircase for residential high-rise buildings. In the case of other buildings, the minimum tread shall be 30 cm. The treads shall be constructed and maintained in a manner to prevent slipping. Winders shall be allowed in residential buildings provided they are not at the head of a downward flight.
g) The maximum height of riser shall be 19 cm. in the case of residential high rise buildings and 15 cm in the case of other buildings They shall be limited to 12 per flight.
h) Handrails shall be provided with a minimum height of 100 cm. from the center of the tread.
i) The minimum headroom in a passage under the landing of a staircase and under the staircase shall be 2.2 m.
j) For building more than 24 m. in height, access to main staircase shall be through a lobby created by double door of one hour fire rating. One of the doors will be fixed in the wall of the staircase and other after the lobby.
k) No living space, store or other fire risk shall open directly into the staircase or staircases.
l) External exit door of staircase enclosure at ground level shall open directly to the open spaces or can be reached without passing through any door other than a door provided to form a draught lobby.
m) The main staircase and fire escape staircase shall be continuous from ground floor to the terrace level.
n) No electrical shafts/AC ducts or gas pipe etc. shall pass through the staircase. Lift shall not open in staircase landing.
o) No combustible material shall be used for decoration/wall paneling in the staircase.
p) Beams/columns and other building features shall not reduce the head room/width of the staircase.
q) The exit sign with arrow indicating the way to the escape route shall be provided at a suitable height from the floor level on the wall and shall be illuminated by electric light connected to corridor circuits. All exit way marking sign should be flush with the wall and so designed that no mechanical damage shall occur to them due to moving of furniture or other heavy equipments. Further all landings of floor shall have floor-indicating boards indicating the number of floor as per bye-law. The floor indication board shall be placed on the wall immediately facing the flight of stairs and nearest to the landing. It shall be of size not less than 0.2 m. x 0.5 m.
r) Individual floors shall be prominently indicated on the wall facing the staircase.
s) In case of single staircase it shall terminate at the ground floor level and the access to the basement shall be by a separate staircase. However, the second staircase may lead to basement levels provided the same is separated at ground level either by ventilated lobby with discharge points at two different ends through enclosures.