LumberCalcs: The Straight-Grain Figures for the Hand-Hewn Builder
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ACX / Marine-Grade Plywood

For projects with one visible face -- boat parts, outdoor furniture, or anywhere one smooth, paintable surface matters and the panel may see moisture.

Runner-up: Baltic Birch · Retake the quiz

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Why this fits you

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  • You need one smooth, finish-ready face -- the back won\'t be seen.
  • The project may be exposed to moisture or humidity.
  • You want a step up in quality from CDX without full hardwood cost.
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ACX plywood has a high-quality A-grade face (smooth, minimal defects, paint or stain-ready) and a lower-grade C-grade back, bonded with exterior glue for moisture resistance. It\'s a common choice for outdoor furniture, boat components, and cabinetry backs where one side shows and the other doesn\'t. True marine-grade plywood goes further, using void-free core veneers for maximum moisture resistance in genuinely wet, marine environments.

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How it compares

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OptionBest forFinishCost
CDX PlywoodStructural sheathingUnfinished, C/D grade faces$
OSBBudget structural sheathingUnfinished, strand pattern$
ACX / Marine-Grade PlywoodOne visible face, moisture exposureA-grade face, C-grade back$$
Baltic Birch PlywoodFurniture, cabinetry, fine joinerySmooth both faces, visible edge plies$$$
MDFPainted trim, indoor cabinetryUltra-smooth, uniform, no grain$$
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Buying checklist

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  • If the project will be submerged or constantly wet, confirm you actually need true marine-grade (void-free core), not standard ACX
  • The back face (C-grade) will have some visible defects -- plan your orientation accordingly
  • Seal cut edges, since even exterior-glue plywood absorbs moisture readily at exposed edge grain
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Run the numbers

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Lumber Cost CalculatorPlywood Calculator
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Frequently asked questions

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What\'s the difference between ACX and true marine-grade plywood?

True marine-grade plywood uses void-free core veneers throughout, built for constant wet/marine exposure, while ACX is a more general exterior-rated panel with a good face and exterior glue -- adequate for most outdoor furniture but not the same standard as true marine-grade.

Can I paint ACX plywood?

Yes -- the A-grade face is smooth and largely free of defects, making it paint- or stain-ready with standard prep.

Does ACX need edge sealing?

Yes, generally -- cut edges expose end grain that readily absorbs moisture even with exterior glue, so sealing or edge-banding exposed edges extends the panel\'s life outdoors.

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Other Plywood Type Finder results

CDX PlywoodOSB (Oriented Strand Board)Baltic Birch PlywoodMDF (Medium-Density Fiberboard)
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