Surveyors span tables for designing roof rafters.
Span flat roof joist.
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.
The full version allows any size.
For pitched roofs flat roofs and ceiling joists.
This demo version is fixed at 1m clear span.
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.
Live load is weight of furniture wind snow and more.
Dead load weight of structure and fixed loads 15 lbs ft 2.
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.
Use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.
Supporting imposed load for access and repair only.
Maximum slop3 10 deg.
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 47 x 120 2 43 2 39 2 27 47 x 145 3 08 3 02 2 87 47 x 170 3 75 3 67 3 42 47 x 195 4 41 4 31 3 92 47 x 220 5 04 4 85 4 41 75 x 170 4 50 4 38 3 99.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
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.
Floor joists flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2.
Also available for the android os.
Flat roof joist calculator.
Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.
These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
Span is clear span between supports.
1 enter joist details 1 1 span and joist spacing.
2 are indicated below.
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.
Usually 400 450 or 600mm but any value can be used up to 610mm max.
Span calculator for wood joists and rafters also available for the android os.
Roof rafter span use this table to determine the maximum lengths of roof rafters based on species and grade of lumber spacing dimensions load and slope.
This is the distance between joist centres.
At least 40mm bearing on supports.
