These spans were calculated using our flat roof joist calculation engine.
Flat roof joist span calculator.
The full version allows any size.
This rafter span calculator is species specific for douglas fir hemlock etc.
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.
This demo version is fixed at 1m clear span.
To size joists and rafters use the maximum span tables for southern yellow pine.
Click on a span to generate a full calculation you can adjust the exact span.
Also available for the android os.
Use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.
While every effort has been made to insure the accuracy of the information presented and special effort has been made to assure that the information reflects the state of the art neither the west coast lumber inspection bureau the american wood council nor its members assume any responsibility for any particular design prepared from this online span calculator.
This span table is to the format and methodology given in bs 5268 7 2.
This is the distance between joist centres.
This is based upon the span of the rafter horizontal span not total rafter length live and dead loads.
For pitched roofs flat roofs and ceiling joists 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.
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.
1 enter joist details 1 1 span and joist spacing.
Flat roof joist calculator.
The truss is a framework consisting of rafters posts and struts which supports your roof.
Span calculator for wood joists and rafters also available for the android os.
The important point to keep in mind when you use your truss calculator is that every truss calculation is completely unique and is based on the size of your roof and its specific dimensions.
Find the column for your dead load and spacing and the row for your timber size to find the permissible clear span in metres.
