If your old joists do not meet the requirements set by the table they are either supported.
Flat roof joist span table uk.
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.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
Span tables for solid timber joists.
For pitched roofs flat roofs and ceiling joists.
This table uses commonly available uk regularised timber depths.
Eurocode 5 span tables for solid timber members in floors ceilings and roofs for dwellings 3rd edition.
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.
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.
Surveyors span tables for designing roof rafters.
Other span tables are based on.
These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
Flat roof with no permanent access and altitude not exceeding 100m 0 75 kn m udl 0 9 kn point load most areas exceeding 100m but not exceeding 200m excluding parts of scotland pennines north east england refer to bs 6399 3 1 kn m udl 0 9 kn point load.
The floor joist span tables are based on the loadings given in the amended version of bs 6399 1 which is an imposed load of either a uniformly distributed load of 1 5 kn m or a concentrated load of 1 4 kn.
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.
Joists under each partition.
Tables 1 and 2 in this chapter are derived from the trada technology ltd.
All the figures are based on the normal loading conditions.
Flat roof joists rafters purlin.
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.
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.
This should be compared to the table.
The section sizes are based on regularised als or cls timber.
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.
