Roof Joist Member Thickness

Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

Roof joist member thickness.

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. Here we have a wood framed gable roof. For low pitch roofs building codes may require larger dimension rafters. Wood beam calculator american wood council website rafter and joist span faq.

Span calculator for wood joists and rafters also available for the android os. The lengths and sizes of joists vary depending on the species and quality of the lumber used. Usually 400 450 or 600mm but any value can be used up to 610mm max usually 400 450 or 600mm but any value can be used up to 610mm max 1 2 timber strength class and joist size. This is the distance between joist centres.

Let s consider a basic gable wood roof framing design. 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. 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. Fire safe construction 3 floor performance and tj pro rating 4 5 section 1.

The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial.