Surveyors span tables for designing roof rafters.
Timber flat roof joist span tables.
These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
At least 40mm bearing on supports.
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.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
Other more complex load condition spans can be determined with our free hyne timber design 7 5 software.
For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3.
Flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2.
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.
For pitched roofs flat roofs and ceiling joists.
Joist breadth 47mm.
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.
Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs.
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 floor joists shall be adequate for the spans and loads and be correctly installed.
Span calculator for wood joists and rafters also available for the android os.
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 is clear span between supports.
Supporting imposed load for access and repair only.
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.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
Solid timber joist sizes are provided in the bs 8103 3 span tables.
View joist rafter tables.
View size selection tables.
Maximum slop3 10 deg.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
