Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings.
Flat roof joists span tables.
Notches are not to exceed 0 125 of the depth of the joist and are to be located between 0 07 and 0 25 of the span from the support.
For pitched roofs flat roofs and ceiling joists.
Surveyors span tables for designing roof rafters.
These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
Should refer to trada document span tables for solid timber members in floors ceilings and roofs excluding trussed rafter roofs for dwellings or ask your lbc surveyor for advice.
Roof truss span tables alpine engineered products 15 top chord 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 2x4 2x6 2x6 bottom chord 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2x4 2x4 2x6 2 12 24 24 33 27 27 37 31 31 43 33 33 46 2 5 12 29 29 39 33 33 45 37 38 52 39 40 55 3 12 34 34 46 37 39 53 40 44 60 43 46 64 3 5 12 39 39 53 41 44 61 44 50 65 47 52 70.
View joist rafter tables.
Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall.
Ceiling joist span use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.
Size of joists mm clear span c16 joist m clear span c24 joist m 47 x 95 47 x 120 47 x 145 47 x 170 47 x 195 47 x 220 1 77 2 40 2 89 3 38 3 87 4 36 2 04 2 75 3 47 4 20 4 93 5 66 floor joists flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2.
Span calculator for wood joists and rafters also available for the android os.
Joists under each partition.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
Maximum clear span of flat roof joists in metres for sc3 timber spacing between joists size of roof joist 400mm 450mm 600mm 47 x 97 1 84 1 81 1 74.
Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch.
