Basic requirements ~
- Lines of all risers to meet at one point, ie. the geometric centre.
- Centre going to be uniform and not less than the going of
adjacent straight flights. - Centre going‡going of adjacent parallel tread.
- Centre going£ 700 (2¾rise) in mm.
- Going at newel post, not less than 75 mm.
- Taper angle of treads to be uniform.
- Clear width at least 770 mm.
nosing overhang (V)
nosing
riser
75mm
min.
going
W/2
clear width W
W/2
handrail
centre
going (Gc)
Rc
string
geometric centre
(intersection
of risers)
E
Key:
Gc = centre going
Rc = radius of arc given by equation (see next page)
= angle subtended by each tread
W = clear width
E = risers meeting point to edge of clear width
V = nosing overhang
Tapered Treads and Winder Flights--1