To calculate maximum spans of additional species of lumber, use the Span Calculator or the Span Tables for Joists and Rafters on the American Wood Council website.

115% load duration for snow loads. 125% load duration for construction loads.

They help you determine how far a wooden beam or joist can span between support points, such as walls or beams, without compromising safety and structural integrity.

Joist and rafter span tables show the maximum distance these framing members can safely cover. The spans listed are based on the specific properties of the wood being used.

Using span tables to size joists and rafters is a straight-forward process when you understand the structural principles that govern their use.

In these Western Lumber Span Tables, Western lumber Fb base values have been adjusted for size by appropriate size factors (CF); no further size-adjustment is necessary.

Explore our comprehensive span tables for joists and rafters. Determine the correct size and spacing for your building project to ensure safety and stability. Find the right span table for …

Learn more about BCI® Joists and our sizing software BC Calc® or view the US East and US West span and size charts.

When determining span, pay attention to these three elements: lumber grade, lumber size, and species type. Below are span tables for various species and projects.

Joist Span Table - Use this table to determine floor joist spans, deck joist span, and floor joist spacing.