Plywood is an engineered wood panel made by gluing several thin veneer layers together, each oriented at a right angle to the one below it. That cross-grain construction adds strength in both directions and limits the shrinking, swelling, and warping that moisture causes in solid lumber. Builders reach for it in furniture, deck building, exterior and interior construction, and custom woodworking. The catch is that not every panel does every job; the wrong grade can fail in weather, bow under load, or bleed knots through paint. Knowing what the stamps, grades, and core types mean before you buy separates a project that lasts decades from one rebuilt in a season, which is why choosing the right plywood starts with understanding the options.
How Plywood Is Manufactured
Manufacturers peel logs into continuous veneer sheets on a rotary lathe, then stack them with the grain running in alternating directions. A typical panel uses an odd number of plies, usually three, five, or seven, so the outer faces run parallel and the panel stays balanced. Heat and pressure cure the adhesive into a rigid, stable board.
Veneer Core and Core Alternatives
Veneer core plywood is the standard, with every layer made from the same peeled wood. Lumber core panels sandwich a solid wood center between veneer faces, which holds screws better at the edges and suits cabinet doors. MDF and particleboard cores give a flat, void-free surface for laminates but weigh more.
How Ply Count Affects Performance
A three-ply panel stays light enough for drawer bottoms and craft work, while seven-ply panels resist racking and carry heavier loads. Structural 3/4-inch panels typically run five plies or more, reducing the chance of a void opening under a fastener.
The visible surface determines how the panel accepts stain and paint, so comparing face grades, wood types, and long-term care before a purchase prevents the classic mistake of buying a rough sheathing panel when the job calls for a sanded face. The trade-offs show up in service: interior-grade panels can contain urea-formaldehyde adhesives, voids in economy grades weaken screw holding, and unsealed edges wick moisture into the core.
The Main Types of Plywood
Plywood splits into two families: softwood panels made from Douglas fir, southern pine, and spruce, and hardwood panels faced with birch, maple, oak, or poplar. Softwood panels dominate structural work because they are strong, inexpensive, and available in big sheets. Hardwood panels carry a premium and go into cabinets, furniture, and visible trim.
Softwood Plywood
CDX is the framing crew’s workhorse, with C-grade faces and D-grade backs, handling wall sheathing, subflooring, and roof decks. Sanded pine plywood, often sold as ACX, offers a smooth face for painted shelving and light furniture.
Hardwood Plywood
Baltic birch, imported from northern Europe, uses more plies of consistent thickness and almost no voids, making it a favorite for jigs, shop fixtures, and visible joinery. Domestic maple, oak, and poplar panels are sold as cabinet grade or furniture grade.
Specialty Panels
Marine plywood uses waterproof adhesive and void-free veneers for boats and exterior exposure, while pressure-treated plywood resists water, insects, and decomposition for ground contact and outdoor framing. MDO, short for medium-density overlay, bonds a resin-treated paper face to the panel for a paint-ready surface on signs, benches, and commercial siding. Regional yards stock different brands and species, so comparing the different types of plywood side by side helps.
How the Common Panels Compare
Typical retail ranges for a 4×8 sheet in the United States; prices shift with the lumber market.
| Panel type | Face and core | Best uses | Typical price, 4×8 sheet |
|---|---|---|---|
| CDX sheathing | C face, D back, veneer core | Wall and roof sheathing, subfloor, crates | $25-$45 |
| Sanded pine (ACX) | Sanded C face, veneer core | Shelving, cabinets, painted furniture | $35-$55 |
| Hardwood cabinet ply | Birch, maple, or oak face | Cabinets, furniture, trim | $50-$100 |
| Baltic birch | Multi-ply birch, void-free | Jigs, shop fixtures, visible joinery | $40-$80 |
| Marine | Waterproof glue, void-free veneers | Boats, docks, exterior exposure | $80-$150 |
| Pressure-treated | Treated softwood veneers | Ground contact, outdoor framing | $35-$60 |
| MDO | Resin-overlaid face | Signs, benches, exterior paint grade | $50-$70 |
Cutting Plywood Without Tear-Out
Plywood cuts differently from solid lumber because the outer veneer is thin and unsupported at the cut line. A dull blade lifts the veneer and leaves a chipped, fuzzy edge that ruins the face; a few setup steps prevent most of the damage.
Blade Selection
A carbide-tipped blade with 40 teeth or more leaves a clean edge in veneer, and a dedicated plywood blade with an alternate top bevel severs the fibers before the tooth back can tear them. Thin-kerf blades remove less material and reduce waste on expensive panels.
Preventing Tear-Out
- Run painter’s tape along the cut line and cut through it; the tape holds the veneer fibers in place.
- Score the line with a sharp utility knife before cutting, deep enough to sever the face veneer.
- Use a zero-clearance insert on a table saw so the blade exits through a narrow slot.
- Set the good face down on a table saw and good face up with a circular saw.
- Clamp a straightedge guide for circular saw cuts instead of freehanding long rips.
Supporting the Sheet
A full 4×8 sheet sags in the middle on two sawhorses, and the sag pinches a table saw blade or binds a circular saw. Lay the sheet on foam insulation board, or keep the cut line near the support so both sides stay level. A track saw or straightedge with anti-slip clamps keeps long rips straight, and a rundown of cutting plywood to size techniques covers the jigs and stops for repeat cuts.
Sheathing, Subflooring, and Structural Use
Most plywood sold in the United States goes into structural assemblies, where it carries roof, wall, and floor loads and ties the frame together against wind and seismic forces. These panels are made to the PS 1-09 standard and stamped with a span rating that tells a framer how far apart supports can be.
Wall Sheathing and Weather Barriers
Structural wall sheathing comes in 7/16-inch and 1/2-inch thicknesses and 4×8 or 4×9 sheets sized to cover the stud bay plus the plates. Conventional practice installs the sheathing, then wraps the walls in housewrap before siding. Integrated systems build the weather barrier into the panel face so the two steps happen at once, and crews deciding between the approaches can weigh zip system sheathing vs. plywood with housewrap on cost, drying ability, and taping labor.
Span Ratings and Thickness
The two-number span rating on the stamp, such as 24/16, means the panel spans 24 inches on center as roof sheathing and 16 inches on center as subflooring. Wall panels need a 24-inch wall rating or better, floors with joists at 24 inches on center call for 3/4-inch tongue-and-groove plywood, and 16-inch spacing accepts 5/8-inch.
Subflooring
Tongue-and-groove subfloor panels lock together so the seams do not flex underfoot, and builders glue them to the joists before screwing or nailing down. A single layer of 3/4-inch plywood works as both subfloor and underlayment for many floor coverings, while tile and stone usually want a second layer or cement board.
Grades, Exposure Ratings, and Sizes
The first letter on a plywood stamp describes the face veneer, and the second letter describes the back. A-grade faces are smooth and nearly free of defects; B-grade allows minor repairs and small tight knots; C-grade permits larger knots and discoloration; D-grade is the roughest, with open knots and voids that are fine behind siding but unacceptable on visible surfaces.
Reading the Grade Stamp
| Grade | Face appearance | Typical use |
|---|---|---|
| A | Smooth, sanded, minimal defects | Cabinets, furniture, visible panels |
| B | Minor repairs, tight knots under 1 inch | Interior trim, cabinet backs |
| C | Knots to 1-1/2 inches, some discoloration | Sheathing, subfloor, crates |
| D | Open knots and voids allowed | Panel backs, hidden structural use |
A panel stamped CDX carries C-grade faces, D-grade backs, and exterior glue, which is why it is the default sheathing panel even though neither face is pretty. This Old House keeps a plain-language types of plywood reference with photographs of each grade.
Exposure Ratings
Exposure ratings describe how much moisture the glue line can take. Exterior-rated panels use fully waterproof adhesive and survive long-term wetting; Exposure 1 panels resist weather during construction delays but suit protected use; Exposure 2 suits dry interiors only. Marine plywood sits above all of them, with waterproof glue and no inner voids.
Standard Sheet Sizes
The familiar 4×8 sheet is the baseline, and 4×9 and 4×10 sheets reduce waste on walls with 9- and 10-foot ceilings. Thicknesses run from 1/4 inch for paneling and craft work through 3/8, 1/2, 5/8, and 3/4 inch for structural work, with 1-1/8 inch for heavy-duty subfloor. Many yards also stock 2×2 and 2×4 handyman panels.
Buying Plywood and Building With It
A good sheet is flat, dry, and free of soft spots. At the yard, run a hand across the face, sight down the edge for cupping, and check the stamp against the job. Panels stored on edge in a dry rack stay flatter than stacks in a damp lot, and buying from the middle of a stack avoids the sun-warped top sheet.
Cost Reality Check
Plywood averages about $3 per square foot, while solid wood usually starts around $5 on the low end, which is why large projects default to panels. Pairing a cheap CDX core with a sanded hardwood face only where it shows controls a budget. Sanded panels accept paint and stain with minimal prep; unsanded sheathing needs heavy filling first.
Reading the APA Trademark
The APA trademark lists the mill, grade, exposure rating, span rating, and the standard it was made to, usually PS 1-09. Read the stamp in the same order every time:
- Locate the APA trademark on the face or edge.
- Read the two grade letters, such as C-D, left to right.
- Check the exposure rating, labeled Exterior or Exposure 1.
- Confirm the span rating, such as 24/16, against your framing.
- Verify the standard, usually PS 1-09, printed near the trademark.
A stamp with all of those details signals a panel built for structural duty; a faded or missing stamp deserves a second look before it goes into a load-bearing wall.
Workshop Projects and Bigger Structures
Once the panels are home, plywood earns its keep in the shop. A sturdy shop table built from plywood is a weekend project that uses offcuts and leftover sheets, and the same joinery carries into shelving, jigs, and storage. On the engineering side, high-strength wood panel buildings show how far panelized construction has come, with panels handling loads that once required steel and concrete.