Deck Beam Span Calculator

Inputs

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Actual dressed depth for each built-up ply. Use custom for a measured beam section.
Number of 1.5 in dressed plies assumed to share beam load. Fastening between plies is not checked.
plies
Deck width carried by the beam. For joists from one side only, this is often half the joist span.
ft
Uniform live load on the tributary deck area. Default is an example, not a code table.
psf
Uniform dead load on the tributary deck area, including framing and decking allowance.
psf
Use the adjusted modulus required by your design basis. Default is an example only.
Mpsi
Adjusted allowable bending design value for the selected species, grade, size and deck conditions.
ksi
Adjusted allowable shear design value. Default is an example only.
ksi
For L/360, enter 360. Applied to live-load deflection only.
For L/240, enter 240. Applied to live plus dead load deflection.
Deck beam span between posts or supports to check against the same bending, shear and deflection criteria.
ft

Results

Default result
Edit inputs
Max deck beam span(L_allow)
9.75ft
Pass

Governing deck beam span check: bending stress.

Minimum of bending, shear, live-deflection and total-deflection spans.

Also computed

Post-spacing utilization(U_max)Pass0.6732

Utilization at the entered post spacing (2-ply 2x10 built-up beam).

Bending-controlled span(L_b)9.75ft

Shear-controlled span(L_v)16.65ft

Live-deflection span(L_delta,L)11.36ft

Total-deflection span(L_delta,T)12.07ft

Total beam line load(w)300lb/ft

Surface live + dead load multiplied by tributary deck width.

Deck beam preview CHECKED SPAN / ALLOWABLE GOVERNING UTILIZATION 67% utilization 2-ply 2x10 built-up beam
Method notes 4 notes
  • Uses 2-ply 2x10 built-up beam; beam line load is area load multiplied by tributary deck width.
  • Simple-span uniform-load screen only: M = w*L^2/8, V = w*L/2, delta = 5*w*L^4/(384*E*I).
  • Built-up beam width assumes plies share load. This page does not design ply fastening, splices, posts, caps, brackets, lateral restraint, bearing or footings.
  • Enter adjusted E, Fb and Fv values from the same code/design edition and species/grade/treatment/service-condition basis. Defaults are examples, not a span table.

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