The lengths and sizes of joists vary depending on the species and quality of the lumber used.
Roof joist member thickness.
Trus joist tji joist specifier s guide tj 4000 july 2019.
For instance if your roof has a steep pitch you may be able to use 2 inch by 4 inch rafters but if your roof has a low pitch building code may require that you used 2 inch by 6 inch or 2 inch by 8 inch rafters.
Fire safe construction 3 floor performance and tj pro rating 4 5 section 1.
Span calculator for wood joists and rafters also available for the android os.
Continuing on from part 3.
Here we have a wood framed gable roof.
Wood beam calculator american wood council website rafter and joist span faq.
Floor beam span tables of residential structural design we will now look at roof rafter and beam design.
9 16 tji joists design properties 6 floor span and load tables 7 8 tips for preventing floor noise 8 allowable holes 9 cantilevers 10 11 roof span and load tables 12 13 framing.
Let s consider a basic gable wood roof framing design.
Also available for the android os.
This is the distance between joist centres.
The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial.