Subfloor Thickness Calculator
Determine the minimum and recommended subfloor panel thickness based on joist spacing, floor material, and load type.
How to Use the Subfloor Thickness Calculator
- Select the joist spacing (400 mm or 600 mm).
- Select the subfloor material (plywood, OSB, or concrete).
- Select the load type (residential or commercial).
- Click Calculate to see minimum and recommended thickness.
Casi d'Uso
- •Selecting correct subfloor panels for new floor construction.
- •Checking subfloor adequacy before installing heavy flooring.
- •Planning structural upgrades for commercial fit-outs.
- •Cost estimation for subfloor materials.
Formula
Minimum thickness is determined by joist spacing, panel material, and live load category per structural tables.
Domande Frequenti
What is the most common subfloor thickness?
18 mm (3/4 inch) plywood or OSB is standard for 400 mm joist spacing in residential applications.
When do I need a thicker subfloor?
Wider joist spacing, commercial loads, or heavy equipment require greater panel thickness to prevent deflection.
Is it free?
Yes, all calculators on OhMyCalc are completely free.