Table 4B.21: Maximum clear span of rafters

Table 4B.21 Maximum clear span of rafters (m); Roof pitch more than 22.5° but not more than 30°; Imposed load 0.75 kN/m2; Timber strength class C24. Dead Load [kN/m2] excluding the self weight of the rafter. Rafter sizes in C24 include 38 x 100, 38 x 125, 38 x 150, 47 x 100, 47 x 125, 47 x 150, 50 x 100, 50 x 125, 50 x 150 (all in mm). Rafter sizes in CLS/ALS include 38 x 89, 38 x 140. Spacing of rafters: 400, 450, 600 mm. Dead load categories: Not more than 0.50, More than 0.50 but not more than 0.75, More than 0.75 but not more than 1.00 kN/m2. Table provides maximum clear spans in metres for each combination of rafter size, spacing, and dead load.