To start with here s a great calculator that can calculate the joist spacing based on species of wood joist size and joist spacing.
Shed roof joist size.
This is based upon the span of the rafter horizontal span not total rafter length live and dead loads.
This rafter span calculator is species specific for douglas fir hemlock etc.
The lengths and sizes of joists vary depending on the species and quality of the lumber used.
To size joists and rafters use the maximum span tables for southern yellow pine.
How best to insulate a flat roof of a brick built shed.
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.
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.
Rafter and joist span faq.
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.
Structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.
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.
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.
The full version allows any size.
Enter a specific joist size 2 loadings dead load.
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.
Flat roof joist calculator.
1 enter joist details 1 1 span and joist spacing.
Trying to find what size lumber to use.
More roof calculators roof truss calculator.
This demo version is fixed at 1m clear span.