Typical spans and loading for floor joists of general structural
grade †
Dead weight of flooring and
ceiling, excluding the self weight of the joists (kg/m^2 )< 25 25†50 50†125
Spacing of joists (mm)400 450 600 400 450 600 400 450 600Sawn size
(mm¾mm) Maximum clear span (m)
(^38) ¾ 75 1.22 1.09 0.83 1.14 1.03 0.79 0.98 0.89 0.70
(^38) ¾ 100 1.91 1.78 1.38 1.80 1.64 1.28 1.49 1.36 1.09
(^38) ¾ 125 2.54 2.45 2.01 2.43 2.30 1.83 2.01 1.85 1.50
(^38) ¾ 150 3.05 2.93 2.56 2.91 2.76 2.40 2.50 2.35 1.93
(^38) ¾ 175 3.55 3.40 2.96 3.37 3.19 2.77 2.89 2.73 2.36
(^38) ¾ 200 4.04 3.85 3.35 3.82 3.61 3.13 3.27 3.09 2.68
(^38) ¾ 225 4.53 4.29 3.73 4.25 4.02 3.50 3.65 3.44 2.99
(^50) ¾ 75 1.45 1.37 1.08 1.39 1.30 1.01 1.22 1.11 0.88
(^50) ¾ 100 2.18 2.06 1.76 2.06 1.95 1.62 1.82 1.67 1.35
(^50) ¾ 125 2.79 2.68 2.44 2.67 2.56 2.28 2.40 2.24 1.84
(^50) ¾ 150 3.33 3.21 2.92 3.19 3.07 2.75 2.86 2.70 2.33
(^50) ¾ 175 3.88 3.73 3.38 3.71 3.57 3.17 3.30 3.12 2.71
(^50) ¾ 200 4.42 4.25 3.82 4.23 4.07 3.58 3.74 3.53 3.07
(^50) ¾ 225 4.88 4.74 4.26 4.72 4.57 3.99 4.16 3.94 3.42
(^63) ¾ 100 2.41 2.29 2.01 2.28 2.17 1.90 2.01 1.91 1.60
(^63) ¾ 125 3.00 2.89 2.63 2.88 2.77 2.52 2.59 2.49 2.16
(^63) ¾ 150 3.59 3.46 3.15 3.44 3.31 3.01 3.10 2.98 2.63
(^63) ¾ 175 4.17 4.02 3.66 4.00 3.85 3.51 3.61 3.47 3.03
(^63) ¾ 200 4.73 4.58 4.18 4.56 4.39 4.00 4.11 3.95 3.43
(^63) ¾ 225 5.15 5.01 4.68 4.99 4.85 4.46 4.62 4.40 3.83
(^75) ¾ 125 3.18 3.06 2.79 3.04 2.93 2.67 2.74 2.64 2.40
(^75) ¾ 150 3.79 3.66 3.33 3.64 3.50 3.19 3.28 3.16 2.86
(^75) ¾ 175 4.41 4.25 3.88 4.23 4.07 3.71 3.82 3.68 3.30
(^75) ¾ 200 4.92 4.79 4.42 4.77 4.64 4.23 4.35 4.19 3.74
(^75) ¾ 225 5.36 5.22 4.88 5.20 5.06 4.72 4.82 4.69 4.16
Notes:
- Where a bath is supported, the joists should be duplicated.
- See pages 35 and 36 for material dead weights.
Timber Suspended Upper Floors---Joist Sizes