1. What is Plywood Load Capacity?

The plywood load capacity calculation determines how much weight a plywood sheet can support over a given span before exceeding a specified deflection limit. This is crucial for structural applications like subfloors, roof sheathing, and concrete forms.

2. How Does the Calculator Work?

The calculator uses the plywood load equation:

Where:

• \( Modulus \) — Modulus of elasticity (psi)
• \( I \) — Moment of inertia (in⁴)
• \( Deflection \) — Maximum allowable deflection (in)
• \( Span \) — Distance between supports (in)

Explanation: The equation calculates the uniform load that will produce the specified deflection for a simply supported plywood panel.

3. Importance of Load Calculation

Details: Proper load calculation ensures structural integrity, prevents excessive deflection that could damage finishes, and meets building code requirements.

4. Using the Calculator

Tips: Enter all values in consistent units (psi, inches). Typical modulus values for plywood range from 1,300,000 to 1,700,000 psi. Common deflection limits are L/360 for floors and L/240 for roofs.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical modulus value for plywood?
A: For structural plywood, modulus typically ranges from 1.3-1.7 million psi, depending on grade and species.

Q2: How do I calculate moment of inertia?
A: For a rectangular section, I = (width × thickness³)/12. For 3/4" plywood, I ≈ 0.199 in⁴ per foot width.

Q3: What deflection limits should I use?
A: L/360 is common for floors, L/240 for roofs (where L is span in inches). More stringent limits may be needed for brittle finishes.

Q4: Does this account for live loads?
A: This calculates total allowable load. You must consider both dead and live loads in your design.

Q5: How does plywood thickness affect capacity?
A: Thicker plywood dramatically increases capacity since I is proportional to thickness cubed.