This is the distance between rafter centres.
Flat roof rafter span tables uk.
Span tables for rafters to bs 5268 7 5 imposed loads of 0 75 kn m snow load are applicable to most areas where the altitude does not exceed 100.
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.
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.
Flat roof joists rafters purlin span tables rafters.
Also available for the android os.
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 are there any brittle finishes e g.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
Maximum clear span of rafters in metres for roof pitches of between 15 and 45 degrees.
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.
Contact a building control officer for advice.
Supporting imposed load for access and repair only.
Plasterboard on the underside of the rafter.
Surveyors span tables for designing roof rafters.
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.
Span calculator for wood joists and rafters also available for the android os.
Flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2.
For pitched roofs flat roofs and ceiling joists.
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.
Joist breadth 47mm.
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.
Maximum slop3 10 deg.
At least 40mm bearing on supports.
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.
