Detailed design of stairways

a Width

No stair may be less than 44 in (1118 mm) wide. All stairs from a floor should be approximately the same width to achieve an even distribution of exiting load. b Landings

The landings must be the same width as the stairs, except that landings connecting flights in a straight run need not be more than 48 in (1 219 mm). c Headroom

Clear headroom measured vertically from the nosing of a stair or floor landing must not be less than 6 ft 8 in (2 032 mm). d Vertical rise

Maximum vertical rise between landings or intermediate platforms: 12 ft (3 658 mm). e Treads and risers

There are no regulations regarding pitch.

Maximum riser: 7 in (178 mm) Minimum riser: 4 in (102 mm) Minimum going: 11 in (279 mm) No winders allowed. f Handrails

Handrails should present a continuous gripping surface without obstructions such as newels. There must be a clear 11 in (38 mm) from rail to wall and the rail may project into the stair a maximum of 32 in (88 mm). The rail must be no more than 38 in (965 mm) above the stair nosing or landing floor and no less than 34 in (864 mm).

Handrail ends must continue horizontally at least 12 in (305 mm) beyond the top nosing of a flight. At the bottom of a flight the handrail must continue at the same slope for the equivalent of one tread beyond the bottom nosing and then continue horizontally for a minimum of 12 in (305 mm). Intermediate handrails are required so that no part of a stair is more than 30 in (762 mm) from a handrail. g Guardrails

In educational buildings the guard rails at stairs and landings should not be less than 42 in (1 067 mm). In all other use groups, minimum height: 34 in (864 mm). Open guards (i.e. open balustrades) should have balusters or other construction that will not pass a 4 in (102 mm) sphere.

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