Plywood Calculator Guide

Sheets, Waste & Span Ratings for Roof Decking

This guide walks through using a plywood / OSB calculator to scope a roof decking job. Topics include picking the right sheet thickness for your rafter spacing (15/32" plywood or 7/16" OSB for 24" o.c.), calculating sheet count from total roof area (each sheet covers 32 sq ft), choosing a waste factor (10% simple, 15%+ complex), and accounting for cuts at hips, valleys, and the starter row. Includes a span-rating lookup table from the APA Engineered Wood Association.