Using Plywood for Shelves

Using plywood for shelves is very popular. You may have come here trying to figure out why, or just wanting to know why to use plywood in general. Plywood gets a bad rap sometimes. Personally, I think that to some the term means any product that isn’t “pure” unadulterated wood. Note, I purposely chose not to use the term “solid”. Due its construction process, plywood is technically considered “solid wood”.

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Full Disclosure: You will find on this site I frequently reference PureBond plywood. I like this brand and am most familiar with it. They manufacture a product of very high quality using a soy-based adhesive with no formaldehyde. The formaldehyde-free adhesive provides a stronger and more moisture resistant product with no toxic fumes or off-gassing in your home when your project is complete. At times PureBond has sponsored posts or classes I have taught, however, this post about plywood for shelves is not sponsored by them in any way.

What is plywood?

In the most simple explanation, plywood is essentially layers of solid wood bound together with glue. Outside layers are covered with the most attractive layers (called veneer). Exotic wood species (and thus more expensive) can be used to create a very visually appealing or unusual product.

In plywood, the grain of each layer is laid at a 90° angle to the one above or below it. This creates a tremendous strength relative to the thickness of the final product. It also cuts down on total movement so it remains straight over a longer span. Plywood can be painted, stained, drilled, glued, and essentially treated like solid wood in building projects.

Plywood grading

Just like lumber (which I talk about in my post about lumber), plywood has a grading system. It will generally consist of two letters- one for each side.

• A: Sanded smooth, paintable with minimal preparation. There may be minor repairs or seams visible, though finding “perfect” isn’t terribly difficult.
• B: Solid surface with some repairs- generally patches shaped like footballs. May have some splits or tight knots up to 1 inch (though no chunks of wood missing)
• C: Some splits and discoloration, knotholes up to 1 inch, tight knots up to 1 1/2 inch in diameter. Used when appearance is not important.
• D: Some splits, generally no repairs, knots and knotholes up to 2 1/2 inches
• Exterior: specifically designed for outdoor use. Exterior rated products are treated with chemicals to withstand moisture and extreme caution should be used when cutting. Changes to the products used to pressure treat wood products are resulting in higher incidences of skin reactions. PLEASE use proper breathing protection always and specifically when cutting pressure-treated products- I personally recommend long sleeves as well. The rash you can get from pressure treated lumber is no joke and takes a few days to subside.

Other options for shelves

Wood Boards

Being constructed from one long span of a tree, wood boards are dependent on the grain for their strength. They can be subject to movement and/or twisting over time. When building, this needs to be accounted for in the construction process. Additionally, the cost for solid wood goes up substantially as required pieces get longer and thicker. Wood boards are stainable and paintable.

OSB

(Oriented Strand Board) is made of pieces and chunks of wood, pressed and glued together. It is commonly used for subfloors (though not under tile where cement board or hardibacker is required). It is stainable and paintable, though it would be quite difficult to get a smooth finish. The chunks, strands, and pieces of wood create a very unique and discernable pattern in a finished project.

MDF

(Medium Density Fiberboard) is an engineered wood product composed of small wood fibers and a binder compressed in high heat. Because the fibers are so small there are no knots, grain or rings visible. It is far more dense than plywood (and thus much heavier) and does create a stronger material. However, mdf requires a very good oil-based sealer before painting, as it is prone to swelling when exposed to water or moisture. Because of its density, mdf will dull saw blades quickly. It is quite easy to obtain a smooth finish and can be veneered and painted though not stained.

Particle board

Constructed of very small wood chips, particles and wood dust that is pressed and glued together. Particle board is more brittle, does not hold nails well, and can be broken easily with bare hands. Its softness makes it useful as a subfloor or underlayment for carpeting, but would be completely inappropriate for wood floors. Like MDF, particle board will also swell )or even decinegrate) with moisture exposure and must be sealed with oil-based products prior to use. Particle board can be veneered or painted, but not stained. It is commonly found in inexpensive furnishings and cabinetry.

Is plywood for shelves a good idea?

I personally think plywood for shelves is ideal. The smooth feel and appearance is attractive, it maintains a straight line over a long span when properly supported, and can hold more weight than the same size solid wood board.

Because of the way it is sold, plywood also requires less work to make wider or deeper boards thus being quite a bit less expensive to use in construction- when including the costs of both labor and time.

What size plywood do I need?

Plywood is most commonly sold in 4×8′ sheets of varying thicknesses. The most common are 1/4, 1/2, and 3/4 inch sizes or a close equivalent (3/8″, 15/32″ or 12mm, 23/32″ or 18mm).

Hardware stores are now carrying “project panels” as well. The same thicknesses but in smaller overall sizes. Usually 2×4′ or 2×8′ though some versions are available as 4×4 as well. These options are ideal if only needing a small amount, are worried about how to get a large piece home in a smaller vehicle, or desire to use a more exotic or expensive wood species. For example, PureBond has Alder, Cedar, Cherry, Hickory, Mahogany, Maple, Poplar, Red Oak, Walnut, and White Oak available at Home Depot. They can in some instances be a special order product at the big box stores, though can be received rather quickly.

Obviously once you calculate the needed cuts for your project, you need to decide the best thickness. To determine that you will need some basic information (it’s alright if it isn’t exact):

How long of a span will your shelves be?

How often will support be required before shelves will start to sag? If this isn’t something you know or understand, there is a fantastic online calculator I use all the time called the Sagulator.

As a general rule, the heavier the items you will be placing on the shelves, the thicker the recommended product will need to be. The most common size used in shelving is a 3/4 inch thickness. Cabinetry, furniture, and smaller decorative projects might generally use a combination of 1/2 and 3/4 and occasionally 1/4 inch.

Finishing plywood for shelves.

When deciding how to finish your plywood shelf project, consider the end location and use. In a damp location such as a bathroom, laundry room (or even at times a kitchen), you want to seal plywood against damage from water. If painting, an oil-based primer and or enamel-style paint does this very well. If desiring a wood-grain look, one can use a stain to change the color or just seal it for protection. For this, an oil-based polyurethane or specific product designed for water resistance (such as Waterlox) is ideal.

In a closet or general home setting, water or moisture is not necessarily as much of a concern. Water-based finishes will work quite well (I recommend a separate primer on raw wood surfaces when painting- especially outdoors).

Edges

If the layered look of the plywood ends bothers you, using pieces of trim or edge banding veneer hides them while leaving the appearance of an unadulterated wood board. Veneer bandings usually adhere with a hot-melt adhesive activated with a household iron or heat gun, and both types of edge trim can be finished in the same way you would finish plywood- stained, painted, or just sealed.

Finally

My goal with this post is to encourage you to use plywood for shelves and in projects without fear. Plywood is a more economical, environmentally friendly, and durable alternative to wood boards, while still maintaining an ease of use and many finish options.

Let me know if you have any other questions or topics you would like to see covered, and… Happy Building!

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