Technical Booklet D Structure·Page 44·Table 4B.25
Maximum clear span of rafters
Table 4B.25 provides maximum clear span values in metres for timber rafters of various sizes on roofs pitched between 22.5° and 30°, with an imposed load of 1.00 kN/m² and timber strength class C24. Spans vary based on rafter size, spacing, and dead load category.
Table 4B.25 Maximum clear span of rafters (m); Roof pitch more than 22.5° but not more than 30°; Imposed load 1.00 kN/m2; Timber strength class C24
Dead Load [kN/m2] excluding the self weight of the rafter, with spacing of rafters (mm) at 400, 450, 600.
Rafter sizes C24: 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.
Rafter sizes CLS/ALS: 38 x 89, 38 x 140.
Dead load categories: Not more than 0.50 kN/m², More than 0.50 but not more than 0.75 kN/m², More than 0.75 but not more than 1.00 kN/m².
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