Building Construction Handbook, Eighth Edition

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