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Deck joist span calculator for wood

Calculator presetASD, NDS 2024

Design a wood deck joist in Calcs.com. Start from the Deck Joist preset, set your size and span, and check bending, shear, bearing and deflection to NDS 2024.

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How deck joist design works in Calcs.com

The Deck Joist preset sets up the Wood Beam (ASD, NDS 2024) calculator in Calcs.com, a standards-aligned calculation platform for structural engineers.

[ 01 ]

Start from the Deck Joist preset

Choose Wood Beam (ASD), then Deck Joist. You start from the member you're designing, with its loads and limits in place, rather than a blank beam. Deck Joist is a floor joist moved outdoors: wet service, and the Minimum Balcony/Deck Live Load the calculator sets from your building code. Each value below is where the preset starts. You can change any of them.

  • Loads

    Starts with Floor Load: dead 10 psf, live 60 psf, over a 16 in spacing. Change any value or the spacing, or add line, point and moment loads.

  • Deflection limits

    Starts at L/360 for live load and L/240 long term. Set the limits your project calls for.

  • Service condition

    Starts wet, for an exterior member. Set it to dry for a member kept dry in service.

  • Member and bracing

    Starts as a repeating member, top braced for lateral torsional buckling. Change the plies or the bracing to match your framing.

Wood Beam (ASD) presets in Calcs.com, with Deck Joist picked

[ 02 ]

Change it to your deck joist

Pick a size and grade from the standard sections database, enter a custom section, or let Autosize choose one. Then set the plies, span, supports and bracing.

  • Size and grade

    Standard lumber, glulam, LVL, PSL and LSL sections, or a custom section, with Autosize beside the size field.

  • Span and supports

    Plan length, support type, position and bearing length for each support.

  • Bracing and flitch plates

    Continuous bracing for lateral torsional buckling, and optional flitch plates.

Design conditions for the Deck Joist preset in Calcs.com: IBC 2024, horizontal, repeating member, with the wet service condition highlighted

[ 03 ]

See every check as you design

Bending, shear and bearing utilization sit at the top of the sheet. Deflection is checked against the limits the preset sets.

Loads for the Deck Joist preset in Calcs.com: 10 psf dead and 60 psf live over a 1.33 ft width on a 10 ft joist, with the 60 psf minimum balcony and deck live load highlighted

Try the deck joist preset: change the size and span

Pick a size and a span. The sheet shows what the Wood Beam (ASD, NDS 2024) calculator returned for that deck joist.

  • Utilization at a glance

    Bending, shear and bearing as percentages at the top of the sheet, as in the calculator.

  • Deflection against the preset's limits

    Live load and long-term deflection checked against L/360 and L/240.

  • Every check, as the calculator prints it

    Moment, shear and bearing utilization and both deflections, with the value behind each percentage.

14-day free trial • No credit card required

Wood Beam (ASD, NDS 2024) - Deck JoistSavedJ1
Bending54%Shear30%Bearing26%

Key Properties

Size and Grade
Number of Plies =
Beam Plan Length =ft
Minimum Balcony/Deck Live Load =60 psf
Center-to-Center Spacing (= tributary width) =in
Distributed LoadsFloor Load: dead 10 psf, live 60 psf
Continuous Bracing for Lateral Torsional Buckling
Service ConditionDryWet

Checks

Moment Utilization =1207 lb-ft / 2255 lb-ft54%
Shear Utilization =483 lb / 1615 lb30%
Bearing Utilization =483 lb / 1884 lb26%
Governing Live / Short-Term Deflection =-0.119 in (L/1009)36%
Governing Long-Term Deflection =-0.143 in (L/836)29%

Plies, spacing, loads and bracing are as the Deck Joist preset sets them. Every input is editable in the calculator. This sheet replays 12 solves by the Calcs.com engine on 2026-11-12: 3 sizes by 4 spans. In the calculator, any size, span, spacing or load is solved the same way.

Deck joist span table: 2x8 to 2x12

Each cell is the Deck Joist preset solved in the Wood Beam (ASD, NDS 2024) calculator at that size and span, with every other input as the preset sets it. It shows the governing check's ratio. Above 1.00 fails.

Deck joist span table, governing check ratio by member and span
Member8 ft10 ft12 ft14 ft
2x80.60BendingPasses0.93BendingPasses1.34BendingFails2.03Live load deflectionFails
2x100.34BendingPasses0.54BendingPasses0.77BendingPasses1.05BendingFails
2x120.26BendingPasses0.40BendingPasses0.58BendingPasses0.79BendingPasses

13 presets on one wood beam calculator

Each member preset, from Floor Joist to Deck Beam, sets up the same calculator with its own loads and deflection limits. Rafter and Hip / Valley put the member on a slope. Deck Joist and Deck Beam set wet service.

Open the Deck Joist preset in the calculator

  1. [ 01 ]Start your free trial. You land on the app's home page.
  2. [ 02 ]Open the Wood Beam (ASD) calculator for the edition you design to.
  3. [ 03 ]Choose Deck Joist from its presets. Its values load in, ready to change.
See the full Wood Beam (ASD, NDS 2024) calculator
Edition

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Pick the edition you design to. The sheet and the steps above follow it, and each edition has a Deck Joist preset.

These results use the preset's loads and limits. Check every input against your project before you rely on a result. The engineer of record stays responsible for the design.

Frequently asked questions

Design your deck joist in Calcs.com

Start from the Deck Joist preset and check your size and span to NDS 2024.

Design your deck joistSee the full Wood Beam (ASD, NDS 2024) calculator
Linking a calculation to a column in Calcs.com, with the AISC Steel Construction Manual reference attached

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