Plywood Grades Explained

The face letter grades: AA down to D

Hardwood plywood is governed by ANSI/HPVA HP-1, the American National Standard for Hardwood and Decorative Plywood, issued by the Decorative Hardwoods Association (the trade group most of the industry still calls HPVA out of habit). The system rates the two faces of a sheet on two separate scales, and the face scale runs on letters.

A is matched for both grain and color, with veneer splices book-matched so there is no abrupt jump between them. No sound knots, no repaired knots, no rough-cut veneer are allowed, though a little mineral streak and vine marking pass. This is the grade a shop reaches for when the grain has to read as one continuous piece across a door or panel run.

B is matched for pleasing color but not necessarily grain, and allows some sound or repaired knots and a bit of rough-cut veneer. Columbia Forest Products markets this tier as an everyday "cabinet grade," and for most kitchens it is the workhorse choice.

C is a sound, smooth face that allows unlimited pin knots and small burls, repaired and sound knots, and unlimited mineral or vine marks. This is paint-grade and cabinet-interior territory, the face you cover rather than show.

D carries the same tolerances as C, plus some rough-cut veneer and a few more repairs. It is the economy tier, and some suppliers (States Industries among them) print a fifth face grade, E, below it, for surfaces that will be fully hidden or are meant to read as rustic. Other sources stop the ladder at D. Treat D and E as "everything below C, increasingly forgiving" rather than a sharp line - different mills draw it slightly differently.

Above A sits a tier the base standard does not officially name but the trade sells constantly: AA, or "double A," described as nearly flawless with uniform color and grain and minimal to no patches. States Industries, Columbia Forest Products and TT Plywood all publish and sell AA as a real premium tier, above A, for architectural paneling and high-end case goods. It is a supplier convention layered on top of the formal standard rather than a letter every source lists independently, but it is universal enough in the trade to treat as real.

The back number grades: 1 to 4

The other face gets its own independent rating, on a number scale rather than letters. 1 is sound with tight knots only, up to 3/8 in across, no repaired knots and no open defects. 2 allows sound knots up to 3/4 in plus repaired knots and rough-cut veneer, still with no open defects. 3 is looser again, meant for a back that has to stay presentable without being the show face: cabinet sides, drawer sides, shelving that can carry some stain or spliced veneer.

4 is commonly called a "reject back": open knots, filled knots, bad veneer seams, knot holes up to 4 in, and open splits are all fair game. It shows up almost exclusively on thin, 1/4 in panels for parts nobody will ever look at, like drawer bottoms and the inside of a cabinet back.

Put the two scales together and a code reads exactly as it looks. A-1 or A-2 are "good two-sided" panels for anywhere both faces show, with the number side carrying a little more tolerance than a true letter grade would. A-3, B-3 and C-3 pair a show face with a back clean enough not to look bad edge-on, correct for cabinet ends and drawer sides. A-4, B-4 and C-4 pair a show face with a reject back, exactly right for a drawer bottom. Grading each face independently also means a genuinely unusual panel like C-1, a cheap show face on a premium-clean back, is a real product, not a typo.

G1S and G2S: a different question entirely

CabDesign's own Materials Library carries a separate field for this, and it is worth knowing why. G1S ("Good One Side") and G2S ("Good Two Sides") come out of the softwood and construction sanded-panel tradition, not the hardwood face-veneer tradition above. Richmond Plywood Corporation, a working mill, describes G1S as an A-grade face over a C-grade utility back, built to a Douglas Fir plywood standard and sold as a general-purpose sanded panel for furniture, cabinet doors, shelving and even concrete forms.

The distinction that actually matters at the saw: G1S/G2S answers how many faces need to look good, while the letter/number system answers how good the good face actually looks. A panel can be G2S, meaning both faces are show faces, and still be graded anywhere from AA down to C on the quality axis underneath - a G2S-AA panel and a G2S-C panel are both "good two sides" and worlds apart in price and appearance. Shops have borrowed G1S/G2S as everyday shorthand even for hardwood veneer sheet goods because it answers the coverage question in one word, which is exactly why it is worth keeping as its own field rather than folding it into the quality ladder.

Baltic birch runs its own ladder

Baltic birch is not graded under ANSI/HPVA HP-1 at all. It comes out of a separate Russian and Baltic mill convention, and unlike the domestic hardwood system, the grading in practice describes only the outer veneer's appearance, not the core. The common ladder, best to worst: B/BB (a clear, defect-free single-piece face over a back with a few small color-matched patches, the top commercially common tier), BB/BB (the most commonly stocked grade, both faces allowing a handful of small matched patches), BB/CP (a BB face over a downgraded back that allows unlimited patches and sound knots), CP/CP (both faces sound but utility-grade, meant for laminating rather than a fine show face), and C/C (the bottom tier, structural use only).

Baltic birch's B tier behaves more like hardwood plywood's A or AA, a clean single-piece face, than like a hardwood back grade. Reading the two ladders as interchangeable, or assuming a Baltic birch "B" sits at the same quality as a hardwood "B," will mislead you. If your materials library stocks Baltic Birch, give it its own set of veneer-grade options rather than force-mapping its letters onto the HPVA scale.

Why this is not CDX

The letters look the same as hardwood plywood's A-D face grades, and that resemblance is exactly what causes the mix-up: CDX's A-D describes structural soundness, not how the wood looks. A cabinet shop occasionally reaches for an A-face G1S fir panel for jigs, templates or rough utility work, but this whole system is essentially never specified for finished casework. The hardwood-veneer system above - birch, oak, maple, walnut, veneer- or MDF-core - is what actually gets built into cabinets. Never treat the two A-D letter scales as one system; they promise different things.

Melamine and MDF: there is no ladder to argue about

There is no ANSI-equivalent, cross-supplier grading standard for melamine, thermally fused laminate (TFL), or MDF the way HP-1 governs hardwood veneer plywood. Individual mills market their own melamine panels with informal "Grade A" language for a smooth, blemish-free surface, but that is marketing shorthand, not an audited standard. Raw MDF and particleboard are not appearance-graded at all, because there is no wood veneer face to grade - the surface is uniform machined fiber, later covered by melamine, laminate, veneer or paint. If you are speccing one of these, the honest move is to skip the face-grade field entirely rather than force a plywood-style code onto a panel type that structurally has no face veneer to grade.

The whole point of getting these codes straight is that they are cheap insurance. Reading A-1 on an invoice and knowing exactly what both faces are allowed to look like, before the sheet ever reaches the saw, is the difference between a plan and a surprise.

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