These spans were calculated using our flat roof joist calculation engine.
Roof joist span calculator uk.
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.
In snowy areas your roof should be at least 10 12 40 to allow snow to shed while the safest roof pitch in very windy areas is between 4 12 6 12 18 5 26 5.
Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
For a gothic style the rafters must equal the span 60 while an elizabethan style requires the rafters to be longer than the span.
Span calculator for wood joists and rafters also available for the android os.
You will be given a range of depths and centres that are available and also an indicative deflection result.
For pitched roofs flat roofs and ceiling joists.
If supporting lightweight partitions running parallel to joists provide two additional joists under each partition.
This span table is to the format and methodology given in bs 5268 7 2.
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.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
These span tables are the equivalent of other industry standard span tables and are calculated to the same standards.
Also available for the android os.
Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors.
This table uses commonly available uk regularised timber depths.
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.
Surveyors span tables for designing roof rafters.
Simply enter the required span to see a range of results that will work.
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.
