Deck Board Span Calculator
Calculate maximum allowable deck board span based on species strength, board thickness, and load requirements
Select a species and board dimensions to calculate maximum span.
Formulas Used
Allowable Bending Stress
Fb = MOR / 2.5
The allowable fiber stress is the wood's breaking strength divided by a safety factor of 2.5.
Maximum Span (Bending)
L = √(8 × Fb × S / w)
Where S is section modulus (b×d²/6) and w is the load per unit length.
Deflection Limit
L/360 = 5wL⁴ / (384EI)
The span is limited so deflection doesn't exceed L/360 under live load.
