🧱 Plywood Wall Sheathing Calculator — Openings & Shear Walls

Net vs rough: two ways to answer the same wall

The calculator shows both counts at once because the right answer depends on the crew, not the math. Net mode deducts every opening and buys only the sheathing that stays. Rough mode sheathes over the openings and cuts them out later — one sheet more or less, but a different workflow on site. Here is the trade-off in full:

Most framing crews sheath over window openings and cut later, keeping the full-sheet offcuts for gable ends — that is why the calculator defaults to Net for the order but prints the Rough count beside it. Buy the Rough number when the cutouts will be reused; buy the Net number when they will not.

Common opening deductions

The three openings that cover most walls, pre-loaded in the calculator’s add-buttons. Sizes are rough-opening-ish field standards — a 3×6.67 door is the classic 32" slab in a 36" rough frame.

Thickness by stud spacing

Walls are the most forgiving application for panel thickness — spans are short and loads are mostly lateral — so the table is simple, and the nail column matters as much as the thickness column because shear capacity lives in the nailing schedule:

🧱Panel edges land on framing — every one of them

Panel edges land on framing — every one of themPhoto: Unsplash

Shear walls: the nailing schedule is the capacity

The same panel that merely covers a wall can also brace it against wind and seismic loads — but only when the fastening schedule says so. Shear capacity is set by panel type, nail size, and edge spacing in that order; thickness by itself contributes surprisingly little. APA’s ASD reference values:

* Allowable Stress Design reference values from APA published tables. Above ~510 lb/ft, or in High Seismic / 140 mph wind zones, capacity must come from APA EWS documentation or a licensed engineer — not a website table.

The rounding floor: why small openings save nothing

Sheets are whole objects, so deductions save material only in whole-sheet steps — a threshold effect the calculator’s two-mode display makes visible. One 15 sq ft window on a 40×8 wall moves the net count from 8.44 to 8.03 effective sheets: both round up to the same order at 10% waste. Two windows on the same wall cross the threshold and return one real sheet. The practical rules:

• 1.Per-wall, not per-house: deductions apply within each wall’s own layout — a window on the front wall cannot donate its savings to the blank rear wall.
• 2.Cluster before you cut: walls with several openings are where Net mode earns its keep; single-opening walls usually round the same either way.
• 3.Gable ends are the exception: a blank 24×9 gable eats odd triangles — over-order by the waste input, not by hope, or run the triangles through the cut layout calculator.

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