Technical Booklet D Structure·Page 38·Table 4B.13
Table 4B.13: Maximum clear span of rafters
This table specifies the maximum clear spans in metres for timber rafters of various sizes. The table applies to roof pitches between 15° and 22.5°, an imposed load of 0.75 kN/m², timber strength class C24, and various dead loads and rafter spacings.
Table 4B.13 Maximum clear span of rafters (m); Roof pitch more than 15° but not more than 22.5°; Imposed load of 0.75 kN/m2; Timber strength class C24 C24
Dead Load [kN/m2] excluding the self weight of the rafter
Size of rafter (mm): 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, 38 x 89, 38 x 140, CLS/ALS
For three 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
For spacing of rafters: 400, 450, 600 mm
Spans range from 1.68 m to 3.93 m depending on rafter size, dead load, and spacing.
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