Span tables for solid timber joists. Span ft 1 5 2 0 2 5 3 0 3 5 2 30 22 18 15 13 4 59 44 36 30 25 6 89 67 53 44 38 8 119 89 71 59 51 10 148 111. Surveyors span tables for designing roof rafters.