Surveyors span tables for designing roof rafters.
Flat roof timber span tables uk.
The section sizes are based on regularised als or cls timber.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
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.
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.
They also tell you what the maximum spacing should be between each section or timber member 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.
Span tables flat roof joists 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.
Subject ceilings and flat roofs timber sizes and construction details 09 issued 01 04 13 rev page 1 of 2 the following tables give details of the allowable spans and spacing for some of the more common timber sizes used in ceiling and flat roof construction.
Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
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.
For pitched roofs flat roofs and ceiling joists.
For timber floors between homes.
Span tables for solid timber joists.
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.
Span tables span tables can be used to determine the size of a timber member of a particular strength class required for a given span.
All the figures are based on the normal loading conditions.
These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
Tables 1 and 2 in this chapter are derived from the trada technology ltd.
