Free Engineering Tool

Structural Timber
Load Calculator

Preliminary beam sizing for Douglas Fir timbers. Enter your span, loads, and timber size — get instant bending, deflection, and shear results.

⚠ For preliminary sizing only. All permitted structures require review by a licensed Professional Engineer.

Calculator Inputs

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Structural self-weight + permanent fixtures

Occupancy / snow / roof (typical floor = 40 psf)

Width of floor/roof area loading this beam

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Applies CM = 0.85 reduction factor per NDS. Auto-selected for green timber.

Results

Enter values and click Calculate

NDS Design Values — Douglas Fir-Larch

PropertySelect StructuralNo. 1No. 2
Fb — Bending1,500 psi1,200 psi975 psi
Ft — Tension1,000 psi825 psi625 psi
Fv — Shear170 psi170 psi170 psi
Fc — Compression1,150 psi1,000 psi825 psi
E — Modulus1,600,000 psi1,600,000 psi1,300,000 psi

Table 4D — NDS Supplement. Wet service factor CM = 0.85 applied when green timber selected.

This calculator is for preliminary sizing only. Results are based on simplified beam equations and NDS 2018 design values for Douglas Fir-Larch. All permitted structures require review and stamped drawings by a licensed Professional Engineer registered in your jurisdiction. Washington Timber Company assumes no liability for structural calculations or design decisions made using this tool.