Free Roof Sheathing Calculator — Sheets & Cost (2026)

How to Use This Calculator

1. 1Calculate roof area (slope length × roof length × 2 for gable, or use a slope factor).
2. 2Click Calculate — includes H-clip count.

About This Material

Roof sheathing creates the structural deck that supports roofing underlayment, shingles, and all roof loads. The standard material is 7/16-inch OSB for 16-inch rafter or truss spacing, and 1/2-inch OSB or CDX plywood for 24-inch spacing. Panels are 4x8 feet (32 sq ft each) and are installed horizontally starting from the eave, with staggered end joints between rows. H-clips — small metal clips inserted between panel edges at mid-span — are required wherever unsupported panel edges span between rafters or trusses to prevent sagging under load. OSB roof sheathing costs $15 to $30 per sheet, while CDX plywood runs $25 to $45. In regions with frequent wind-driven rain, radiant barrier sheathing (OSB with a reflective foil face) helps reduce attic heat gain. Always use Exposure 1-rated panels since roof sheathing may be exposed to weather during construction. The nailing schedule is critical for wind uplift resistance — 8d nails at 6 inches on edges and 12 inches in the field.

Installation Tips

• •Start from the eave, working toward the ridge.
• •Stagger end joints between rows.
• •Leave 1/8" expansion gaps at all edges.
• •Install H-clips at mid-span between rafters/trusses.

Common Mistakes to Avoid

• ⚠Forgetting H-clips — required for 24" OC framing.
• ⚠Not staggering end joints.
• ⚠Using interior-rated OSB in wet climates — use Exposure 1 or exterior rated.

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