Flat Roof Rafter Span Tables Uk

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 rafter span tables uk.

Plasterboard on the underside of the rafter. At least 40mm bearing on supports. Maximum slop3 10 deg. These span tables apply only to flat roof and roof with a slope of up to 10 degrees.

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. Contact a building control officer for advice. 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. Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.

This is the distance between rafter centres. Flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2. 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. Span calculator for wood joists and rafters also available for the android os.

Span is clear span between supports. Maximum clear span of rafters in metres for roof pitches of between 15 and 45 degrees. For pitched roofs flat roofs and ceiling joists. 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.

Joist breadth 47mm. Surveyors span tables for designing roof rafters. Supporting imposed load for access and repair only. 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.

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. Flat roof joists rafters purlin span tables rafters. 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.