They also tell you what the maximum spacing should be between each section or timber member.
Roof span tables uk.
These span tables are the equivalent of other industry standard span tables and are calculated to the same standards.
This span table is to the format and methodology given in bs 5268 7 2.
Maximum clear span of rafters in metres for roof pitches of between 15 and 45 degrees.
Span tables for ceiling joists to bs 5268 7 3 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.
Contact a building control officer for advice.
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.
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 05 2 67 3 22 3 77 4 31 4 85 assumptions at 400mm centers.
Span tables can be used to determine the size of a timber member of a particular strength class required for a given span.
Refer to approved document to part a of the building regulations on gov uk for heavier roofing materials or unusual loading conditions these tables may not be appropriate.
This table uses commonly available uk regularised timber depths.
Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.
These spans were calculated using our flat roof joist calculation engine.