Plywood and OSB Sheathing Span Rating

Allowable spacing / live load / total load from APA span-rating tables; pass/fail against user-supplied design loads.

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Formula and source

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.

Audience

This tile is built for carpentry and the adjacent professions in the Carpentry and Construction group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.

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Posture

Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.