Structural Panel Span Ratings
Span TableAPA-rated structural panel span ratings for roof sheathing and subflooring. Shows maximum support spacing by panel span rating and thickness.
Roof Sheathing — Maximum Span (inches o.c.)
Source: APA — The Engineered Wood Association, Form V345| Span Rating | Min. Thickness (in.) | Max. Rafter Spacing | Max. Live Load (psf) | Edge Support Required |
|---|---|---|---|---|
| 24/0 | 3/8 | 24" | 40 | Yes — H-clips or T&G |
| 24/16 | 7/16 | 24" | 40 | Yes — H-clips or T&G |
| 32/16 | 15/32 | 32" | 40 | No (≤24" spacing) |
| 40/20 | 19/32 | 40" | 40 | No (≤32" spacing) |
| 48/24 | 23/32 | 48" | 40 | No |
Subflooring — Maximum Span (inches o.c.)
Source: APA — The Engineered Wood Association, Form V345| Span Rating | Min. Thickness (in.) | Max. Joist Spacing | Fastening Schedule | Glue Recommended |
|---|---|---|---|---|
| 24/16 | 7/16 | 16" | 6" edge / 12" field | Yes |
| 32/16 | 15/32 | 16" | 6" edge / 12" field | Yes |
| 40/20 | 19/32 | 20" | 6" edge / 12" field | Yes |
| 48/24 | 23/32 | 24" | 6" edge / 12" field | Yes |
Applicable Codes & Standards
- • IRC R503.2.1 — Structural panel subflooring
- • IRC R803.2.1.1 — Structural panel roof sheathing
- • IBC 2304.7 — Wood structural panels
- • APA Form V345 — Design/Construction Guide: Residential & Commercial
- • PS 1-19 — U.S. Voluntary Product Standard for Structural Plywood
- • PS 2-18 — Performance Standard for Wood Structural Panels
How to Read This Table
Span ratings are stamped on every APA-rated structural panel. The format "32/16" means the panel can span up to 32 inches between roof supports and 16 inches between floor supports. These ratings assume the panel's strength axis (long dimension) runs perpendicular to the supports.
Important Notes
- These spans assume normal occupancy loads. Heavy concentrated loads (like a waterbed or aquarium) may require closer spacing or thicker panels.
- Edge support (H-clips or tongue-and-groove edges) is required when panel edges fall between supports at spans ≥24 inches.
- Glue-nailed subflooring systems significantly reduce squeaks and increase stiffness compared to nails alone.
- Always check local amendments — some jurisdictions require minimum 7/16" roof sheathing regardless of span rating in high-wind zones.
For the most current ratings and detailed engineering values, refer to APA Technical Note N375 or contact the APA directly at apawood.org.