Boise Cascade Beam Calculator

Example Data Table

Formula Used

The calculator uses simple span beam mechanics with rectangular section properties.

• Uniform line load: w = area load × tributary width + line loads
• Area: A = b × d
• Section modulus: S = b × d² / 6
• Moment of inertia: I = b × d³ / 12
• Bending stress: fb = M / S
• Rectangular shear stress: fv = 1.5V / A
• Bearing pressure: fp = reaction / bearing area
• Deflection limit: allowable deflection = span in inches / selected limit

Point load and combined deflection are estimated by numerical integration of the beam curvature. This helps support off-center point loads.

How To Use This Calculator

1. Enter the clear span between supports.
2. Add tributary width, dead load, live load, and extra line load.
3. Add any single point load and its location.
4. Select a material preset or enter custom design values.
5. Enter beam width, depth, bearing length, and adjustment factors.
6. Press Calculate Beam.
7. Review utilization ratios, reactions, stress checks, and deflection checks.
8. Download the CSV or PDF result for project records.

Boise Cascade Beam Calculator Guide

A beam decision affects floors, roofs, walls, openings, and cost. This calculator helps you test a simple span before formal design. It uses common mechanics for engineered wood members. It is not an official Boise Cascade sizing table. It also does not replace local code checks. Use it as a planning aid, then confirm the final member with approved literature, stamped drawings, or a licensed professional.

What The Tool Checks

The form compares applied demand with entered design values. You can model uniform floor load, roof load, extra line load, beam weight, and one point load. It calculates reactions, maximum shear, maximum moment, bending stress, shear stress, bearing pressure, and estimated deflection. The result section also shows utilization ratios. A ratio below one usually means the entered value is not exceeded. A ratio above one needs review.

Inputs That Matter Most

Span controls bending and deflection strongly. A small span increase can create a large demand increase. Tributary width controls how much area load reaches the beam. Beam depth improves stiffness quickly because inertia grows with depth cubed. Width helps bending, shear, and bearing. Material values control allowable resistance. Always enter values from the exact product grade, depth, use condition, and load duration.

Reading The Result

Start with reactions because they affect posts, hangers, and bearing plates. Then check bending and shear. Next, review deflection. A beam can pass strength but still feel bouncy or crack finishes. The deflection limit should match the use. Floors often need tighter limits than temporary framing. Roofs may need separate live, snow, or total checks.

Good Practice

Measure clear span correctly. Include permanent dead loads. Add construction loads when they are relevant. Do not ignore concentrated loads from posts above. Check bearing length at each support. Review lateral restraint, notches, holes, fire rating, moisture exposure, vibration, and connection capacity. Save the CSV or PDF for discussion with your designer, supplier, or inspector before ordering material.

For remodels, collect field notes before changing framing. Note species, member depth, support type, fasteners, and visible damage. Existing beams may carry hidden loads from stairs, chimneys, tanks, or bearing walls. When in doubt, reduce assumptions early and ask for project specific verification too.

FAQs