Plywood Subfloor Types: Best Grade, Thickness & Comparison
For most residential subfloors, 23/32" (3/4") tongue-and-groove CDX plywood is the correct choice — it fits 16" on-center joists, resists moisture better than OSB (swells less than 5% vs. 15%), and interlocking edges prevent squeaking without blocking. Use the wrong grade or thickness and your finished floor will flex, squeak, or fail at the joints within a few years. This guide covers every plywood subfloor type by grade, thickness, moisture rating, and which finished floor each one supports.
⚡ Quick Answer: Best Plywood for Subfloor
Use 23/32" (3/4") tongue-and-groove CDX plywood, APA-rated Exposure 1, for standard residential subfloors on 16" on-center joists. Step down to 5/8" for joists at 12" OC. Use marine-grade plywood in bathrooms and basements. CDX outperforms OSB in moisture resistance — plywood swells less than 5% vs. OSB at 15% in ASTM D1037 tests.
Types Of Subfloor Materials
Subfloor plywood is structural-grade plywood installed directly over floor joists to create a flat, rigid base layer for finished flooring. It is rated by the American Plywood Association (APA) by span (e.g., 24/16) and exposure class (Exposure 1 or Exposure 2), which determines how well the glue bonds hold under moisture exposure.
Plywood is a popular choice for subflooring due to its strength, durability, and ease of installation. It also has excellent water and mold resistance compared to other materials like OSB or particle board. Tongue and groove CDX plywood is the recommended option for most residential subfloor installations.
📊 Subfloor Plywood By the Numbers
Standard thickness: 23/32" (3/4") for 16" OC joists | 5/8" minimum for 12" OC | Plywood moisture swell: <5% vs. OSB at 15% (ASTM D1037) | CDX is ~10% stiffer than comparable OSB | Marine-grade cost: $80–$130/sheet vs. CDX at $35–$55/sheet
Choosing The Best Plywood For Subfloor
When choosing the best plywood for subfloors, match grade to moisture exposure and thickness to joist spacing. Plywood is stronger and more durable than OSB and particle board. Tongue and groove is the best plywood subfloor type for preventing floor deformation and squeaks. Here is how each grade compares:
| Plywood Grade | Best For | Standard Thickness | Moisture Rating | Approx. Cost/Sheet |
|---|---|---|---|---|
| CDX T&G (Exposure 1) | Residential standard — all floor types | 23/32" (3/4") | Good — swells <5% | $40–$60 |
| CDX (flat edge) | Subfloor with blocking at joints | 23/32" (3/4") | Good | $35–$55 |
| ACX (Exposure 1) | Higher appearance areas, kitchens | 3/4" | Better | $50–$70 |
| Marine Grade | Bathrooms, basements, wet areas | 3/4" | Excellent — near-zero swell | $80–$130 |
| Structural (5-ply) | Garages, lofts, heavy loads | 3/4"–1" | Good | $55–$80 |
| OSB (comparison) | Dry budget installs only | 23/32" | Fair — swells 15% | $25–$40 |
Top Pick
3/4" Tongue-and-Groove CDX Plywood (APA Rated)
The residential standard for subfloor installations. APA Exposure 1 rated, 23/32" T&G, span-rated 24/16. Interlocking edges eliminate blocking and prevent squeaks. Available in 4×8 sheets at most lumber yards.
Check Price on Amazon →Why Plywood Is Better Than Other Subfloor Materials
Plywood outperforms other subfloor materials across every key metric — moisture resistance, strength, longevity, and screw-holding ability. Here is why builders consistently choose plywood over the alternatives:
Plywood vs. OSB: Plywood swells less than 5% when exposed to moisture vs. OSB at 15% (ASTM D1037 testing). CDX plywood is approximately 10% stiffer than a comparable OSB panel because of its cross-laminated veneer construction, and it holds screws and nails more securely over time. In kitchens, bathrooms, and any moisture-prone room, plywood is the safer long-term choice.
Plywood vs. Particle Board: Particle board absorbs water rapidly and crumbles — it is not rated for structural subfloor use and will fail under normal foot traffic in any area with humidity variation. It should never be used as a primary subfloor layer.
Plywood vs. Solid Wood Planks: Solid dimensional lumber used as subflooring (common in older homes) can cup, shrink, and develop gaps over time as it dries. Plywood’s cross-laminated construction gives it bidirectional strength and dimensional stability that solid planks cannot match. Tongue-and-groove plywood also distributes point loads across multiple panels, reducing bounce and flex under foot.
Bottom line: For residential subfloors, 3/4" CDX T&G plywood is the best-performing, most widely available option. OSB is acceptable only in consistently dry areas where cost is the primary concern. Particle board is never appropriate. In wet areas, step up to marine-grade or pressure-treated plywood.
Comparison Of Plywood And Osb
Plywood is a strong and durable option for subfloors, with excellent water and mold resistance. It is also stronger per unit weight than OSB, making it a preferred choice. Tongue and groove flooring plywood is recommended for the best performance.
Plywood is the preferred subflooring material compared to OSB due to superior dimensional stability. Let’s take a closer look at some of the key differences between these two popular subflooring options.
Moisture Resistance
When it comes to moisture resistance, plywood is the clear winner. Plywood is made from multiple layers of wood veneer bonded with waterproof glue. CDX plywood (Exposure 1) is designed to handle temporary moisture exposure during construction. OSB, by contrast, can swell up to 15% at the edges when wet — a problem that rarely fully reverses even after drying. In kitchens, bathrooms, or any area near a water source, CDX or marine-grade plywood is the correct choice over OSB.
Strength
Plywood’s cross-laminated veneer construction makes it approximately 10% stiffer than a comparable OSB panel. It also holds fasteners — screws and nails — more securely over time, reducing the risk of squeaking as the floor settles. For joists spaced 19.2" or 24" on center, plywood maintains rigidity better than OSB at the same thickness.
Installation Ease
Both plywood and OSB install the same way — staggered 4×8 sheets fastened with ring-shank nails or screws, with construction adhesive on each joist. Tongue-and-groove versions of both products simplify installation by eliminating the need for blocking at panel edges.
Thickness Requirements
Match thickness to joist spacing: 19/32" (5/8") minimum for 12" OC joists, and 23/32" (3/4") for 16" OC. When joists are spaced 24" on center, 3/4" becomes the minimum for both plywood and OSB. For added stiffness under tile or hardwood, some builders use 1-1/8" T&G plywood over 24" OC framing.
Common Subfloor Materials
Plywood is a strong and durable subfloor material commonly used in construction projects due to its ease of installation. It is also resistant to water and mold, making it a popular choice over other materials like OSB or particle board.
When it comes to installation of flooring systems, subfloors play a critical role in ensuring that the final surface is strong, stable, and capable of handling the weight of the finished floor and foot traffic. Here are the most common subfloor materials used in residential construction:
Water and Mold Resistance
CDX plywood (Exposure 1) resists moisture at the construction site level. Marine-grade plywood resists prolonged water contact. Both outperform OSB in mold resistance because plywood’s veneer layers are less porous than OSB’s compressed wood fiber structure. In high-humidity climates or over unvented crawl spaces, always use plywood rated Exposure 1 or better.
Custom Subfloor Systems
Custom subfloor systems offer a variety of plywood subfloor types to suit every construction project. Plywood is the most popular choice for subfloors due to its durability, strength, and resistance to water and mold. Custom subfloor systems may combine plywood with additional layers for specific flooring applications.
Dura Foam
Foam underlayment panels combined with plywood subfloor create a thermal and acoustic barrier — common in basement conversions and slab-on-grade installations where floor heating is not present. The plywood structural layer sits above, maintaining rigidity while the foam reduces heat loss and sound transfer.
Thermal Brake
Thermal break systems use a composite plywood-foam panel to prevent cold transfer from concrete slabs. These are common in northern climates where concrete slab temperatures can cause moisture condensation and discomfort in finished living spaces. See our guide to floor heating costs for an overview of systems that pair with thermal break subfloor panels.
DIY System
DIY subfloor systems typically use standard 3/4" T&G CDX plywood with construction adhesive and 1-5/8" screws at 8" spacing along joists. For a concrete slab subfloor, use a floating system with 3/4" plywood over 6-mil poly vapor barrier. See how to install wood flooring on concrete slab for the full technique.
Benefits Of Different Subfloor Materials For Different Floors
Different finished floors have different subfloor requirements. Here is what each floor type needs from a plywood subfloor:
Tile
Tile requires a very stiff, stable subfloor with minimal flex — deflection over 1/360 of the span will crack grout lines. Use 3/4" T&G plywood plus a 1/4" cement board underlayment, or a single layer of 1-1/8" T&G plywood over 16" OC joists. See how to install wood-look tile flooring for subfloor prep requirements.
Concrete
On concrete slabs, plywood subflooring is installed as a floating system over a vapor barrier to prevent moisture wicking from the slab. Use 3/4" plywood with 6-mil poly and leave a 1/8" expansion gap at walls. This creates a warm, resilient base for hardwood, LVP, or carpet. For more on joist span calculations, use our calculator to determine proper subfloor thickness for your framing layout.
Finished Wood Floors
Solid hardwood flooring requires a minimum 3/4" plywood subfloor with no bounce or flex. The plywood grain should run perpendicular to the hardwood grain direction for maximum stiffness. For engineered hardwood or LVP, 5/8" minimum is acceptable if joists are at 16" OC and the subfloor is flat to within 3/16" over 10 feet.
Frequently Asked Questions For Plywood Subfloor Types
What Type Of Plywood Should I Use For Subfloor?
Use 23/32" (3/4") tongue-and-groove CDX plywood, APA-rated Exposure 1, for standard residential subfloors on 16" on-center joists. CDX offers the best balance of strength, moisture resistance, and cost. For bathrooms and basements, upgrade to marine-grade plywood. Tongue-and-groove edges are strongly recommended — they lock panels together, eliminate the need for blocking, and prevent squeaking.
Should I Use 5/8 Or 3/4 Plywood For Subfloor?
Use 3/4" (23/32") plywood for joists at 16" on center — this is the residential standard for virtually all flooring types including hardwood, tile, LVP, and carpet. Use 5/8" only when joists are spaced 12" on center. For joists at 19.2" or 24" OC, 3/4" remains the minimum and some builders step up to 1" or double-layer for extra stiffness under tile.
What Is The Most Common Subfloor?
3/4" CDX plywood is the most common subfloor material in residential new construction. OSB is used in some tract housing due to its lower cost in dry climates. In older homes (pre-1970s), solid 1x diagonal board sheathing was the standard — if you are refinishing an older home, check for board gaps or rot before installing any finished floor directly over old subfloor boards.
Should I Use Tongue And Groove Plywood For Subfloor?
Yes — tongue-and-groove plywood is strongly preferred over flat-edge panels for subfloor. T&G edges interlock to prevent the panel edges from deflecting unevenly under foot traffic, which eliminates the most common source of squeaking in new floors. T&G also creates a stiffer floor system overall and removes the need for blocking at the midspan of joists.
Is CDX Or OSB Better For Subfloor?
CDX plywood is better for most subfloor applications. CDX swells less than 5% with moisture exposure vs. OSB at 15% (ASTM D1037), and CDX is approximately 10% stiffer per panel. CDX holds screws and nails more securely over time, reducing squeaking as the house settles. OSB is acceptable only in consistently dry areas where budget is the primary constraint.
How Thick Should Subfloor Plywood Be?
Subfloor plywood thickness depends on joist spacing: use 19/32" (5/8") for joists at 12" OC, 23/32" (3/4") for joists at 16" OC, and at minimum 3/4" — ideally 1" — for joists at 24" OC. For tile installations, add a 1/4" cement board layer over the plywood subfloor to meet the L/360 deflection requirement. Never use less than 5/8" for any structural subfloor application.
Conclusion
Overall, when considering the best subfloor material for your next project, plywood is the excellent choice. Its durable, moisture-resistant, and easy-to-install properties make it a popular choice for residential and commercial projects alike. Whether you are using CDX T&G for a standard bedroom floor, marine-grade for a bathroom, or a thermal-break system over a concrete slab, matching the right plywood type to your specific conditions will give you a subfloor that performs for decades.
