Tempo:
139 Stair detail tread run projection = 25 mm (1in.) effective tread depth: = minimum tread depth less 15 mm (19⁄32 in.)
rise
leading edge (nosing): width of rounded or bevelled edge = 25 mm (1 in.) riser
A change in direction can be made with landings or winders. Figure 140 shows different types of stairway designs. If winders are used, they must form an angle of either 30°, (three treads for a maximum allowable 90° turn), or 45° (two
treads for a maximum allowable 90° turn). Only one set of such winders is permitted between floor levels. Experience has shown that 30° winders are easier to negotiate than 45° winders.
140 Types of stair layouts
width total run total rise Straight
long L
wide L
double L with 30˚ winders and landing
narrow U
wide U
rise
leading edge (nosing): width of rounded or bevelled edge = 25 mm (1 in.) riser
A change in direction can be made with landings or winders. Figure 140 shows different types of stairway designs. If winders are used, they must form an angle of either 30°, (three treads for a maximum allowable 90° turn), or 45° (two
treads for a maximum allowable 90° turn). Only one set of such winders is permitted between floor levels. Experience has shown that 30° winders are easier to negotiate than 45° winders.
140 Types of stair layouts
width total run total rise Straight
long L
wide L
double L with 30˚ winders and landing
narrow U
wide U
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