9 Best Of How Big Should Roof Joists Be Free Download. How far can you span a 2x6. Feb 24 2020 The measurements are 12 inches and 16 inches off center rafter-to-rafter.
Dead load per square metre in kNm supported by joists. As a general rule roof joists and other structural members are easy to identify because they are larger than surrounding building materials and clearly provide support. Looking at this table you will see there is a choice in the size of floor joist 2 X 6 2 X 8 2 X 10 or 2 X 12 and there is a choice in the joist spacing 12 16.
For example a joist made from doubled 2 x 6s can span a distance about 25 percent more than a single 2 x 6 but a 2 x 12 can span about 80 percent more than.
A lot depends on the engineering of your truss and your local windsnow loads that your building will have to withstand. See the image below for an example of joists spaced 16. Nails have excellent shear strength. Looking at this table you will see there is a choice in the size of floor joist 2 X 6 2 X 8 2 X 10 or 2 X 12 and there is a choice in the joist spacing 12 16.