Flat roof joist calculator.
Flat roof joist span c24.
Span calculator for wood joists and rafters also available for the android os.
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.
Rafter and joist span faq.
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.
The lengths and sizes of joists vary depending on the species and quality of the lumber used.
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.
Dead load weight of structure and fixed loads 15 lbs ft 2.
Timber floor joists shall be adequate for the spans and loads and be correctly installed.
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.
1 ft 0 3048 m.
Live load is weight of furniture wind snow and more.
This demo version is fixed at 1m clear span.
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.
1 psf lb f ft 2 47 88 n m 2.
This is the distance between joist centres.
Also available for the android os.
Usually 400 450 or 600mm but any value can be used up to 610mm max.
Solid timber joist sizes are provided in the bs 8103 3 span tables.
1 enter joist details 1 1 span and joist spacing.
For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
The full version allows any size.
2 are indicated below.
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.
