Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
C24 flat roof joist span.
400mm 450mm 600mm 97 x 47 1 84 1 81 1 74 120 x 47 2 43 2 39 2 27 145 x 47 3 08 3 02 2 87 170 x 47 3 75 3 67 3 42 195 x 47 4 41 4 31 3 92 220 x 47 5 04 4 85 4 41 170 x 75 4 50 4.
Surveyors span tables for designing roof rafters.
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.
Solid timber joist sizes are provided in the bs 8103 3 span tables.
Size of roof joists spacing of joists.
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.
For pitched roofs flat roofs and ceiling joists.
Timber floor joists shall be adequate for the spans and loads and be correctly installed.
Clear spans for flat roof joists in metres.
They refer to a dead load of not more than 0 5kn m 2 excluding the weight of the joist and an imposed load not exceeding 1 5 kn m 2.
Where the tables do not apply or where there are concentrated loads floor joists should be designed by an engineer in accordance with technical requirement r5.
Click here to download c16 span table leaflet c24 span table our premium grade of carcassing is c24 graded.
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.
Floor joist span tables for surveyors floor construction surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors.
The following span tables are indicative of some of the spans required for domestic floor joists where c16 and c24 strength classes are used.
These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
Span tables for flat roof joists to bs 5268 7 2 imposed loads of 0 75 kn m for maintenance and snow load are applicable where there is no permanent access no fixed ladder or staircase and most areas where the altitude does not exceed 100 metres refer to bs 6399 3.
Stocked at all branches click here to download c24 strength class pdf document.
