You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
Timber flat roof joist span tables.
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.
Joist breadth 47mm.
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 calculator for wood joists and rafters also available for the android os.
Solid timber joist sizes are provided in the bs 8103 3 span tables.
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.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
Span is clear span between supports.
At least 40mm bearing on supports.
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.
Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs.
Other more complex load condition spans can be determined with our free hyne timber design 7 5 software.
Supporting imposed load for access and repair only.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
Timber floor joists shall be adequate for the spans and loads and be correctly installed.
Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders.
View size selection tables.
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.
Flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2.
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.
For pitched roofs flat roofs and ceiling joists.
Maximum slop3 10 deg.
Also available for the android os.
Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
