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.
C24 flat roof joist span.
For pitched roofs flat roofs and ceiling joists.
Timber floor joists shall be adequate for the spans and loads and be correctly installed.
Click here to download c16 span table leaflet c24 span table our premium grade of carcassing is c24 graded.
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.
The following span tables are indicative of some of the spans required for domestic floor joists where c16 and c24 strength classes are used.
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.
Size of roof joists spacing of joists.
Joists under each partition.
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.
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.
Stocked at all branches click here to download c24 strength class pdf document.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
C16 span table only stocked at our mitcham depot.
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 47 x 120 2 43 2 39 2 27 47 x 145 3 08 3 02 2 87 47 x 170 3 75 3 67 3 42 47 x 195 4 41 4 31 3 92 47 x 220 5 04 4 85 4 41 75 x 170 4 50 4 38.
Clear spans for flat roof joists in metres.
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.
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.
