📐 Beam Parameters
FAQ
How do I determine the right beam size?
Beam sizing is governed by three checks: bending strength (S ≥ S_required), live load deflection (≤ L/360), and total load deflection (≤ L/240). This calculator automatically checks all standard sizes and recommends the smallest one that passes all criteria.
What's the difference between SPF, Douglas Fir, SYP, and LVL?
SPF (Spruce-Pine-Fir) is the most economical softwood for standard residential use. Douglas Fir offers slightly higher strength. SYP (Southern Yellow Pine) is stronger still. LVL (Laminated Veneer Lumber) is engineered wood with the highest strength, ideal for long spans.
What do live load and dead load mean?
Live load is variable weight (people, furniture, snow) — standard is 40 psf for residential floors. Dead load is the self-weight of the structure (flooring, ceiling, partitions), typically 10-15 psf.
Why doesn't my beam pass for longer spans?
For spans beyond ~16 ft, deflection (not bending strength) becomes the governing limit. Try tighter spacing (12" O.C.) or higher-grade material (LVL).