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Construction glossary · Wood framing

What is plywood gradesin construction?

Plywood grades are the stamped letter ratings (A, B, C, D) that describe the veneer face quality on each side of a structural plywood panel, paired with an exposure rating and span rating. In framing, the grade tells you whether a panel is meant for hidden structural sheathing or for a finished, visible surface.

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Updated June 2026 · Reviewed by the Ruh construction team

Grade scale A to D facesSheathing pick CDX 15/32 inCabinet pick A-B hardwood plySheet size 4 ft x 8 ft

Plywood face veneer grades, A best to D roughest

A: sanded, smooth,…B: solid, minor re…C: knots, splits a…C-plugged: filled…D: large knots, kn…Common: CDX sheath…CDX = C face, D back, X glue
The definition

Plywood grades, explained.

Plywood is built from thin wood veneers glued in cross-grain layers, and its grade is expressed as two letters, one for the face and one for the back, such as C-D. Letter A is smooth and sanded, B allows minor repairs, C permits knots and small splits, and D allows the largest defects. The most common structural panel is CDX, meaning a C face, a D back, and exterior-grade glue, used for wall and roof sheathing where the surface is hidden. Sanded grades like A-C or B-C cost more and are reserved for finish work where a face will show. Every structural panel also carries an APA stamp with an exposure rating (Exterior or Exposure 1) and a span rating like 32/16. For estimating, you match the grade to the application so you do not pay finish-panel prices for hidden sheathing, and you confirm the exposure rating suits the dry-in schedule.

How it is measured

Plywood is taken off the same way as OSB: gross wall, roof, or floor area in square feet from the elevations, roof plan, and floor plan, divided by 32 sf per 4 ft by 8 ft sheet, then rounded up with a waste factor. The grade and exposure rating come from the wall and roof schedules and the finish schedule, not from the dimensions. Where the drawings call out a sanded or finish-face panel for soffits, exposed ceilings, or cabinet-grade work, those panels are quantified separately because their unit cost is much higher. Always read the APA stamp callout to confirm span rating against framing spacing before pricing.

Worked example

A worked plywood grades example.

Worked example

A job needs sheathing for 1,600 sf of hidden wall plus 200 sf of exposed porch soffit that will be painted and visible. For the hidden walls you spec CDX: 1,600 sf / 32 sf per sheet = 50 sheets, plus 10 percent waste = 55 sheets at an illustrative $32 per sheet = $1,760. For the visible soffit you spec sanded A-C: 200 sf / 32 = 6.25 sheets, plus 10 percent = 7 sheets at an illustrative $58 per sheet = $406. Total plywood is $1,760 + $406 = $2,166. Note that using the $58 sanded panel for all 62 sheets would have cost 62 x $58 = $3,596, so matching grade to application saved roughly $1,430. The estimator verifies the finish schedule before splitting the order.

How Ruh handles it

How Ruh handles plywood grades.

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Plywood grades: frequently asked questions

What does CDX plywood mean?+

CDX is a structural panel with a C-grade face, a D-grade back, and exterior-grade glue. It is the standard choice for wall and roof sheathing where the surface is covered. The X refers to the exterior glue line, not to full waterproof rating.

When do I need a sanded plywood grade instead of CDX?+

Use a sanded grade such as A-C or B-C when a panel face will be visible or painted, such as exposed soffits, ceilings, or cabinet-grade work. For hidden sheathing it is wasted money since the surface is covered.

Do plywood and OSB use the same span ratings?+

Yes. Both carry the same APA span rating system, such as 32/16, where the first number is roof support spacing and the second is floor support spacing. That lets you swap between them structurally at equal rating.

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Related terms

OSB (oriented strand board)SheathingSubfloorFurringNominal vs actual lumber dimensions

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Figures on this page are illustrative. Construction estimates depend on project-specific conditions, source documents, market pricing, and professional judgment. Ruh's AI assists the estimator and does not replace professional review: your team reviews, validates, and approves every estimate, bid, and pricing decision.

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