Plywood and OSB Sheathing Span Rating
Allowable spacing / live load / total load from APA span-rating tables; pass/fail against user-supplied design loads.
Example
You enter
- Panel thickness (in) 0.5
- Span rating 24/16
- Application roof
- Support spacing (in) 24
- Live load (psf) 30
- Dead load (psf) 8
You get
- Allowable spacing 24 in OC
- Allowable live 40
- Allowable total 50 psf
- Spacing pass Yes
- Live pass Yes
- Total pass Yes
- Pass Yes
- Application roof
Details, formula, and sources
Allowable uniform load = lookup(span_rating, application). Pass/fail = (support_spacing ≤ allowable_spacing) AND (live_load ≤ allowable_live) AND (live + dead ≤ allowable_total).
APA - The Engineered Wood Association published span-rating tables by name. Cited by APA name only; numeric tables shipped under APA's technical-bulletin reuse policy. IRC 2021 (International Residential Code). §R503 / §R803 references the APA tables.
APA technical bulletins free at apawood.org/publications.
Estimate. AHJ and licensed structural engineer govern.
Field names used by the API: panel_thickness_in, span_rating, application, support_spacing_in, live_load_psf, dead_load_psf, allowable_spacing_in, allowable_live_psf, allowable_total_psf, spacing_pass, live_pass, total_pass, pass
- Span-rating table data/construction/apa-span-ratings.json keyed to rating × applicationAPA technical bulletins