Hardwood Floors February/March 2025

TECHNICAL PUBLICATION RESOURCES

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NATIONAL WOOD FLOORING ASSOCIATION TECHNICAL PUBLICATION

For additional information, check out the NWFA's Technical Guidelines at NWFA.ORG/TECHNICAL- GUIDELINES/.

How to Read the Specifics on a Wood Subfloor

Panel Grade

Span Rating

Bond Classification

Mill-Thickness

Mill Number

Reference Standards

Mill Number

Performance Category

Reference Standards

Reference Standards

Bond Classification

Bond Classification

Performance Category

Performance Category

Span Rating

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Span Rating

Mill-Thickness

Mill-Thickness

Panel grade: identifies the intended use of the panel. Span rating: maximum for roof spans/maximum for floor joist span.

Bond classification: indicates how much weather and moisture the panel is designed to withstand. Mill-thickness: thickness of the material.

Mill number: Identifies the Mill ID #. Reference standards: industry standard designations. Performance category: nominal thickness of product.

Source: NWFA Wood Flooring Installation Guidelines (revised 2019)

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