Your plywood thickness will determine what projects it is best suited for. This ultimate guide will take you through everything you need to know – from standard measurements to specialized types and practical applications.
Only Have a Minute?
Here’s a rundown of plywood thickness and some common uses:
| Nominal Plywood Thickness | Actual Plywood Thickness (inches) | Actual Plywood Thickness (millimeters) | Common Uses |
|---|---|---|---|
| 1/8″ | 7/64″ | 2.7mm | Inlays, scroll work |
| 1/4″ | 7/32″ | 5.5mm | Drawer bottoms, cabinet backs |
| 3/8″ | 11/32″ | 9mm | Wall sheathing |
| 1/2″ | 15/32″ | 12mm | Furniture, walls, roofing |
| 5/8″ | 19/32″ | 15mm | Floor underlayment, walls, roofing |
| 3/4″ | 23/32″ | 18mm | Subfloors, cabinets, shelving |
| 1″ | 31/32″ | 25.4mm | Table tops |
| 1-1/8″ | 1-1/8″ | 28.1mm | Stair treads, walls (for soundproofing) |
| 1-1/4″ | 1-1/4″ | 30.9mm | Larger projects |
The Ply-Weekly Newsletter
Receive a curated roundup of the best in the world of plywood – every two weeks.
Understanding Plywood
Plywood is a versatile and widely used material that’s integral to various construction and furniture-making projects. Plywood has a layered structure, with each layer, or ply, oriented at a right angle to the one below it. This cross-graining technique gives plywood enhanced stability and resistance to warping, which makes it a reliable choice for many applications.
Plywood in Detail
Plywood is made from layers of wood veneers bonded together under heat and pressure. Each of these layers can be made from hardwood or softwood, contributing to the final attributes of the plywood sheet. Plywood is available in a wide range of thicknesses, commonly starting from as thin as 1/8 inch and going up to 1 inch or more. This allows for a large selection when it comes to picking the right type of plywood for your project, from cabinet-grade plywood that boasts a beautiful finish to thicker structural plywood designed for more demanding construction purposes.
Plywood vs. Other Wood Materials
Plywood offers a more consistent strength across its entire surface due to the cross-grain pattern. Unlike solid wood, which can expand or contract with changes in humidity, plywood remains more stable over time. It generally won’t split or crack as some solid woods might. Particle board is lighter and less expensive but doesn’t offer the same strength or durability as plywood. Plywood sheathing is specifically designed for exterior walls and roofing projects, while thinner plywood might be more appropriate for decorative projects that require a smoother finished surface.
The Importance of Plywood Thickness
The thickness of a sheet of plywood affects the strength, weight, and application possibilities. Thicker plywood offers more stability and support, making it ideal for structural projects like subflooring and roofing ply. Thinner plywood is easier to manipulate and works well for decorative or curved designs.
Plywood sheets come in a variety of thicknesses, often ranging from 1/8 inch to 1 inch. A common misconception is that the labelled nominal thickness, like 3/4 inch, is the actual thickness. However, the actual thickness is slightly less due to the sanding process during manufacturing. So, a sheet labeled as 3/4 inch thick may have an actual thickness of about 23/32 inch.
Here’s a quick reference table for common sizes:
| Nominal Plywood Thickness | Actual Plywood Thickness |
|---|---|
| 1/4 inch | 7/32 inch |
| 1/2 inch | 15/32 inch |
| 3/4 inch | 23/32 inch |
| 1 inch | 31/32 inch |
Choosing the right thickness is essential whether you’re opting for hardwood plywood known for its smooth surface and grain patterns or softwood plywood that’s commonly used for plywood sheathing.
Standard Thicknesses of Plywood
While thickness can range widely, the most common sizes you’ll find at the hardware store include 1/4 inch, 1/2 inch, and 3/4 inch plywood sheets. These are standard across many types of plywood, from structural to cabinet-grade plywood. Manufacturers produce these plywood sheets in large quantities.
Common Thicknesses and Their Uses
A 1/4-inch plywood sheet, with its actual thickness closer to 7/32 inches, is often used for paneling, backing, and crafts where additional flexibility is needed. The 1/2 inch, or an actual thickness of 15/32 inch, plywood provides a good balance between strength and weight, making it suitable for furniture and general construction. The 3/4 inch plywood, about 23/32 inch, is perfect for heavy-duty uses like subfloors, cabinets, and shelving due to its robustness and support.
Odd Thickness Measurements and Their Applications
You may find plywood with an actual thickness of 19/32 inches, which can offer additional support without the weight of a 3/4 inch ply. Sheets as thin as 1/8 inch are available for intricate woodworking projects. Odd thicknesses, such as 5/8 inch or 13/32 inch, often serve specialized purposes, like underlayment or specific furniture components where a precise inch of material is necessary to match with other wood products or to meet design specifications.
Choosing the Right Plywood Thickness for Your Projects
If you’re building a structure that requires a durable surface, thicker plywood would be advisable. Projects that focus on aesthetic detailing might benefit from thinner plywood that is easier to cut and shape. Factoring in the weight load the structure will bear and the type of finishing you intend to apply can also guide your choice.
Factors to Consider When Determining Plywood Thickness
If your project needs to support weight, like shelving or flooring, then you typically need thicker plywood. Hardwood varieties, usually denser, may not require as much thickness as softwood to achieve the same strength. Consider the joining method; thinner plywood can be adequate if you’re employing robust joinery. Remember that the final appearance also matters—if the edges will be visible or contribute to the design, thicker plywood can provide a more substantial look.
Recommended Plywood Thickness for Different Applications
To simplify your decision-making process, here’s a quick guide to recommended plywood thicknesses for various applications:
- Crafting and Paneling: For inlays, scroll work, and backings, consider 1/8 inch to 1/4 inch plywood, which is thin enough for intricate work yet provides some support.
- Furniture: For constructing durable furniture without unnecessary bulk, 1/2 inch to 3/4 inch plywood offers a good mix of stability and weight.
- General Construction: Walls and roofs typically utilize 1/2 inch to 5/8 inch plywood, balancing strength with ease of handling.
- Flooring and Subfloors: Use 3/4 inch plywood for floors to ensure a solid underfoot feeling and to support the weight.
- Cabinetry and Shelving: For cabinets and shelves that bear considerable weight, aim for at least 3/4 inch thickness for maximum strength.
Remember, the specifics of your project may require adjustments to these recommendations. When in doubt, consult with a professional.
Specialized Types of Plywood
Apart from the commonly known softwood and hardwood variations, there’s marine grade plywood designed for high moisture environments, fire-retardant plywood treated to resist combustion, and flexible plywood that can bend for curved structures. Then there’s aircraft plywood, which is made to be exceptionally strong yet light, and structural plywood, which is engineered for high-impact uses in construction.
Hardwood Plywood and Its Different Thicknesses
Hardwood plywood is made from layers of hardwood and is commonly used in the creation of fine furniture and cabinetry. The thickness of hardwood plywood typically ranges from 1/8 inch to 3/4 inch – with 1/4 inch, 1/2 inch, and 3/4 inch being popular choices for many applications. The actual thicknesses might be slightly less due to the sanding process after manufacturing. When a polished, smooth surface is a priority, or a sturdy, yet attractive base is needed, hardwood plywood is the go-to choice.
Softwood Plywood and Its Different Thicknesses
Softwood plywood is generally used for construction projects like walls, roofs, and flooring due to its strength and cost-effectiveness. Made from pine, cedar, or spruce, it can withstand various loads and stresses. The thicknesses range from 1/4 inch for light applications to 3/4 inch and above for more demanding tasks such as subfloors or structural panels. While it doesn’t have the fine finish of hardwood, softwood plywood offers a smooth surface that can be easily painted or stained for a more refined look if needed.
Marine Grade Plywood and Its Applications
Marine grade plywood has exceptional resistance to water and humidity, making it ideal for uses where it will be exposed to the elements, such as in boats, docks, and outdoor furniture. This type of plywood is made with waterproof adhesives and often uses high-quality woods to prevent decay. It usually comes in thicknesses from 1/4 inch to 1 inch to cater to different structural requirements for marine applications. The durability and moisture resistance of marine grade plywood ensure a long-lasting finished product, though it is typically more expensive than other types due to its specialized properties and construction.
Understanding the Actual Thickness vs. Nominal Thickness
When shopping for plywood, you’ll often hear about two types of thickness measurements: actual thickness and nominal thickness. Understanding the difference between them is key to picking the right sheet of plywood for your project.
Nominal thickness is the thickness by which plywood is commonly identified. For example, a sheet might be called a “3/4 inch” piece of plywood, but the actual thickness is often slightly thinner. This is due to the sanding process during manufacturing, which gives the plywood a smooth surface but reduces its dimensions.
The actual thickness can be roughly 1/32 inch less than the nominal thickness. A sheet that’s nominally 3/4 inch might actually measure about 23/32 inch.
Always check the actual thickness marked on the plywood sheet or measure it yourself to be certain of the size. Knowing these differences will help ensure you get the right type of plywood for your construction or woodworking needs.
Plywood Thickness for Wall Sheathing
Wall sheathing is critical for structural stability and weather protection in buildings. Plywood used for sheathing typically ranges between 3/8 inches to 5/8 inches, providing a sturdy layer beneath siding.
Using the right thickness helps ensure the building can withstand environmental stresses and meets local building codes.
Plywood Thickness for Roofing
For roofing, plywood provides a flat, strong base for the application of shingles and other roofing materials. Typical thicknesses range from 3/8 inch to 3/4 inch, depending on the span between rafters or trusses and local codes.
- 3/8 inch: For narrow rafter spacing or temporary fixes
- 1/2 inch: Common choice for standard rafter spans
- 5/8 inch: Added strength for wider rafter spacing
- 3/4 inch: Required for heavy loads or significant snowfall regions
Selecting the right thickness is crucial to prevent sagging and to handle the roofing weight.
Plywood Thickness for Flooring
Plywood serves as a subfloor under your finish flooring material or as the actual flooring itself. Plywood for flooring usually falls between 1/2 inch and 3/4 inch.
- 1/2 inch: Suitable for linoleum or vinyl flooring
- 5/8 inch: Works well under hardwood and carpet
- 3/4 inch: Best for areas with high foot traffic or heavy furniture
Using plywood with sufficient thickness ensures a solid and squeak-free floor.
Plywood Thickness for Furniture and Cabinetry
Furniture and cabinetry benefit from plywood’s smooth surface and wood grain patterns, giving a finished look and structural reliability. Cabinet grade plywood comes in thicknesses like 1/4 inch, 1/2 inch, and 3/4 inch.
- 1/4 inch: For lightweight back panels
- 1/2 inch: For drawer bottoms and structural components
- 3/4 inch: For shelves and supporting structures
For fine pieces or custom work, it’s important to consider both the actual size and the visual appeal of the grain patterns when selecting the plywood thickness.
Plywood Alternatives for Different Projects
Materials like MDF (Medium Density Fiberboard), OSB (Oriented Strand Board), and particle board each come with their strengths and weaknesses. MDF offers a very smooth finish ideal for painting, while OSB boasts greater strength and is commonly used in structural sheathing.
Particle Board vs. Plywood
Particle board is often seen as a cost-effective alternative to plywood. It is made from compressed wood particles and is suitable for light-weight furniture and shelving.
| Aspect | Particle Board | Plywood |
|---|---|---|
| Cost | Generally cheaper | More expensive |
| Strength | Less durable | More durable |
| Moisture | Poor resistance | Better resistance |
| Weight | Lighter | Heavier |
Other Alternatives to Plywood
- MDF (Medium Density Fiberboard): Great for indoor projects, offering a smooth surface for painting.
- OSB (Oriented Strand Board): Excellent for sheathing in construction with superior strength.
- Fiberboard: Suitable for sound insulation and decorative applications due to its density and texture.
