This rafter span calculator is species specific for douglas fir hemlock etc.
Shed roof joist size.
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.
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.
The full version allows any size.
It is always better to have a large rafter rather than be concerned with a sagging roof.
Code of practice for permissible stress design materials and workmanship and bs 5268 7 2 1989 structural use of timber section 7 2.
Structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.
The lengths and sizes of joists vary depending on the species and quality of the lumber used.
Boarding to be fastened on top of flat roof joists with a depth to width ratio greater than 4 the allowable clear spans have been calculated in accordance with bs 5268 2 2002 structural use of timber part 2.
Hi i have a large brick built shed in the garden with an osb felt flat roof with exposed rafters below.
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.
If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.
To size joists and rafters use the maximum span tables for southern yellow pine.
Enter a specific joist size 2 loadings dead load.
Opening up the roof space roof joists.
This is based upon the span of the rafter horizontal span not total rafter length live and dead loads.
Room size is 3m x 3 5m we wish to remove the ceiling to open up the space roof joists are 2x4 50mmx90mm spaced at 1.
Rafter and joist span faq.
1 enter joist details 1 1 span and joist spacing.
In addition this calculator will also allow you to calculate the total number of floor joist needed to complete your shed based on the measurements you provide.
Flat roof joist calculator.
More roof calculators roof truss calculator.