TradesHow this works
Sheathing is just area divided by panel size, plus a buffer for waste. A 4 by 8 sheet covers 32 square feet, so the sheet count is your area plus a waste allowance, over 32, rounded up. The nails come off the sheet count at a standard edge-and-field pattern.
The tool sizes it three ways: exact with no buffer, the recommended allowance for the surface, and a conservative buffer for a cut-up roof or a job far from the supplier. Roofs waste more than walls, so the recommended allowance is higher there. Pick the tier that matches how clean your layout is and how far the yard is.
Common questions
How many sheets of plywood do I need?
A standard 4 by 8 sheet covers 32 square feet, so divide your area by 32 and round up, then add a waste allowance for the cuts. A 640 square foot wall is 20 sheets of coverage, and at a 10 percent waste allowance you would buy 22. The tool does this for walls, roofs, and floors, each with its own typical waste.
How much waste should I add for sheathing?
It depends on the surface. Walls and subfloors run about 10 percent because the cuts are mostly around openings and edges. A roof deck runs higher, around 12 percent or more, because of the rake, hip, and valley cuts that leave offcuts you cannot reuse. A complex layout or a long haul to the yard is worth a conservative buffer.
How many nails for sheathing?
A common fastening pattern is 6 inches on the panel edges and 12 inches in the field, on framing at 16 inches on-center, which works out to roughly 64 nails per 4 by 8 panel. The tool multiplies that by the sheet count and converts to pounds. Your local fastening schedule, especially in high-wind or seismic zones, may call for tighter spacing.
Sources: Panel coverage (evergreen): a 4x8 sheet is 32 sq ft · Nailing: 6 in edge / 12 in field pattern, ~64 nails per panel (typical). Engine version 1.0.0. Risk tier 1.