Building Construction Handbook, Eighth Edition

hip rafter

hip

rafter

ridge board

ridge

board

valley

rafter

valley

rafter

main

rafter

purlin

purlin

jack or

cripple

rafter

hipped end

ridge board

Purlins ~ guide to minimum size (mm) relative to span and spacing:

Span (m) Spacing (m)

1.75 2.25 2.75

2.0 (^125) ¾ (^75150) ¾ (^75150) ¾ 100
2.5 (^150) ¾ (^75175) ¾ (^75175) ¾ 100
3.0 (^175) ¾ (^100200) ¾ (^100200) ¾ 125
3.5 (^225) ¾ (^100225) ¾ (^100225) ¾ 125
4.0 (^225) ¾ (^125250) ¾ (^125250) ¾ 125
Timber Pitched Roofs up to 7.5 m Span--Plan