Measure first
Measure finished dimensions, actual stock, openings, and site constraints before ordering material.
Deck framing
Joist Span Planning Tool
Capture the key dimensions you need before consulting an approved joist span table: clear span, joist spacing, nominal depth, species/grade, and loading conditions. It intentionally does not claim a safe span from a generic formula.
How the estimate works
Use the number as a planning starting point.
The page records the controlling inputs and gives a span-to-depth planning ratio, but an approved table or qualified professional must determine the permitted span for the exact species, grade, load, and code edition.
Check the result
Do not use this page to approve a structural member. Deck framing safety depends on species, grade stamp, loading, bearing, connection, cantilever, notches, holes, and the locally adopted code.
Plan the next step
Use the related calculators below to turn a first estimate into a material list, layout, or a more detailed project plan.
FAQ
Common Joist Span Planning Tool questions
Why does the tool not give a safe joist span?
A safe span depends on code tables and project-specific variables that a simple generic calculator cannot certify.
What information do I need for a joist span table?
Usually species, grade, size, spacing, design load, support condition, and the locally adopted code edition.
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