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.
Timber roof joist span tables uk.
This is the distance between joist centres.
Joist ik mitek d4 adhesive.
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.
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Span tables for solid timber joists.
Joists are to have minimum end bearing of 40mm.
Surveyors span tables for designing roof rafters.
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.
These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
Usually 400 450 or 600mm but any value can be used up to 610mm max usually 400 450 or 600mm but any value can be used up to 610mm max 1 2 timber strength class and joist size.
Proprietary strutting is to be used in accordance with manufacturers recommendations.
These span tables are based on the imposed loads given in bs 5268 7 1 and bs 6399 1 with an imposed uniformly distributed load of 0 25kn m acting together with a concentrated point load of 0 9 kn.
Posi joists mitek manufactures the steel webs used in posi joists.
Floor joist span tables for surveyors floor construction.
Solid timber joist sizes are provided in the bs 8103 3 span tables.
Posi rafters posi rafters combine the lightness of timber and strength of posi strut steel webs to provide a quality roof system that can span further than alternative timber products.
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 220 1 77 2 40.
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.
Joist spans 2 5m to 4 5m provide strutting at mid span.
The weight of the timber floor itself consists of the timber joists the plasterboard ceiling underneath it except for suspended timber ground floors the floorboards and the nails or screws used to fix both of the aforementioned coverings.
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.
For pitched roofs flat roofs and ceiling joists.
Solid timber strutting to be at least 38mm thick and be a minimum of three quarters of the joist depth.
