Flat Roof Timber Span Tables

Span tables use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.

Flat roof timber span tables.

Joist and rafter span tables. Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters. Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders. For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3.

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. 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. 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. View joist rafter tables.

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. Surveyors span tables for designing roof rafters. R cb150 16 beam span table used w 3600 width of frame rafter span χ 6410 fascia beam span the cb150 16 beam achieves the 6000mm span for the fascia beam and can be used for the rafters. You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.

These span tables apply only to flat roof and roof with a slope of up to 10 degrees. Attached flat roof 1ao page14. View allowable load tables. 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.

View size selection tables. Span tables for ceiling joists to bs 5268 7 3 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.