Floor Joist Span Calculator

The SkyCiv floor joist span calculator allows you to calculate the maximum span of timber joints. The calculations in this tool are based on the American Wood Council's standards. The tool considers factors including the joist size, thickness, height, wood type, and wood grade as well as loading and deflection factors. Various common types of wood and grades are available.

Starting Flooring Joist Span Calculator...

About the Flooring Joist Span Calculator

How to use the Calculator?

To begin using the calculator enter the details of the joist on the left-hand side. These details will include:

  • Joist Size
  • Joist Thickness
  • Joist Height
  • On-Center Spacing

Then complete the advanced details including:

  • Wood & Grad
  • Deflection Limit
  • Load per Area Unit

Run the calculator to determine the maximum span

Calculator Assumptions and Limitations:

  • This tool supports only natural solid lumber joists
  • This tool uses the American Wood Council's standards for reference. '
  • These calculations are only approximations and should be used as the starting point to get an idea about the Joist Span.

Frequently Asked Questions:

What is a floor joist span table?

Floor joist span tables are references used by engineers, builders, and construction workers to estimate the appropriate size of joists based on factors such as the joist parameters and floor loading. The above calculator can be used in place of a floor joist span table.

Can floor joist tables be used to calculate the maximum allowable span for timber floor joists?

Yes, floor joist tables are generally available for timber floor joists. The correct table needs to be used based on the type of wood, lumber, or timber joist. Alternatively, the above calculator contains options for many types of wood including:

  • Alaska Cedar
  • Alaska Hemlock
  • Alaska Spruce
  • Alaska Yellow Cedar
  • Aspen
  • Baldcypress
  • Beech-Birch-Hickory
  • Coast Sitka Spruce
  • Cottonwood
  • Douglas Fir-Larch
  • Douglas Fir-Larch (North)
  • Douglas Fir-South
  • Eastern Hemlock-Balsam Fir
  • Eastern Hemlock-Tamarack
  • Eastern Softwoods
  • Eastern White Pine
  • Hem-Fir

How does on-center spacing affect floor joists' maximum span?

The on-center spacing is the spacing between each joist. Generally, the larger the spacing (distance between each joist) then the lower the maximum allowable span is.

Do floor joist span tables and calculators work for wood like LVL (Laminated Veneer Lumber)?

Floor joist span calculators and tables can be used for LVL timber as long as considerations around the material properties and behavior of the lumber are taken into account.

Do floor joist span calculators and tables work for deck joists as well?

Yes, floor joist span calculators and tables can be used for deck design as long as all considerations are taken into account.

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