Selecting the right plywood for your outdoor cabinets is crucial to ensuring their longevity and performance. The material needs to be durable enough to withstand exposure to moisture, UV rays, bugs, and temperature fluctuations. With so many plywood options on the market, it can be challenging to determine what plywood is truly the best for outdoor cabinetry. This article will examine the pros and cons of various plywood grades and types to help you make an informed decision.

Factors to Consider When Selecting Outdoor Plywood

When evaluating plywood for outdoor use, here are some key factors to take into account:

Weather Resistance

The plywood needs to hold up against rain, snow, humidity, and sun exposure. Look for exterior-grade plywood that is water and weather resistant.

Durability

Outdoor cabinets experience more wear and tear than indoor cabinetry. Select a plywood that can withstand impacts, scratches, bugs, and rotting over the years. Hardwood plywoods are generally more durable than softwoods.

Stability

The plywood must resist warping, shrinking, cracking, and delaminating when exposed to moisture and temperature swings. Look for plywood with crossbands that stabilize the wood veneers.

Affordability

Outdoor plywood is more expensive than regular indoor plywood. Consider your budget constraints when selecting the material. Less expensive softwood plywood may be sufficient depending on your needs.

Aesthetics

If the finished look is important, choose a plywood with attractive wood veneers on the face and back. Hardwoods like oak, maple, and cherry provide a richer, upscale appearance compared to basic softwoods.

Top Choices for Exterior Plywood

With these factors in mind, below are some of the best plywood options specifically designed for outdoor use:

Marine-Grade Plywood

Marine plywood is considered the gold standard when it comes to durability and water resistance. It is manufactured with waterproof structural adhesives that resist delaminating. The face and back veneers are also made of durable hardwoods, while the core layers are lower grade softwoods.

The main advantages of marine plywood include:

Constructed with waterproof glues for maximum moisture resistance
Face and back veneers resist damage and wear
Multiple laminations prevent warping and splitting
Created specifically for wet environments

The downside is the premium cost, which can be 2-3 times higher than other plywoods. It also lacks ornamental appeal with its basic wood veneers. But for pure longevity in outdoor wet settings, marine plywood is hard to beat.

Exterior-Grade Plywood

Plywood marketed as “exterior grade” is the most commonly used outdoor plywood. It shares many of the favorable properties of marine plywood:

Water-resistant adhesive bonds
Durable face and back veneers
Stabilizing crossbands
Manufactured for exterior applications

The main advantages include:

More affordable than marine plywood
Wide range of wood veneer choices (oak, pine, cedar, etc.)
Performed well in outdoor settings
Commonly stocked at hardware stores

The downsides are a potential lack of ornamental veneers, and durability that may fall slightly short of true marine plywood. But for many outdoor cabinet projects, exterior plywood offers the best balance of weather resistance, strength, and cost.

Tropical Hardwood Plywood

Plywood constructed from dense tropical hardwoods, such as mahogany and teak, is naturally weather resistant and ultra-durable. The dense grain and high natural oil content repel moisture and prevent rotting or warping. These plywoods are commonly used for boatbuilding and other marine applications.

The benefits of tropical hardwood plywood:

Extremely durable face and back veneers
Naturally weather and rot resistant
Attractive grain patterns and rich color
Can last decades in outdoor use

The downside is the premium cost and limited availability of sustainably harvested tropical wood. The extra durability also may not be essential for some outdoor cabinets. But for long-lasting heirloom quality outdoor projects, tropical hardwood plywood is an excellent choice.

Cedar Plywood

For a natural weather-resistant softwood plywood, western red cedar plywood is a great option. The cedar contains natural oils that act as a preservative against moisture, decay, and bugs. Thicker face veneers better resist damage from the elements.

The pros of using cedar plywood:

Natural rot and insect resistance
Distinctive reddish color and wood grain
Economical softwood option
Easy to find at home centers

The weakness of cedar is lower stiffness and hardness compared to hardwood plywood. Over time, the softer cedar may show dents and wear more easily. But the natural weather resistance provides an economical choice for outdoor cabinets.

Pressure-Treated Plywood

Regular plywood is infused with preservative chemicals under high pressure to create pressure-treated plywood. This helps protect against fungal rot and insect attacks. Common treatments include CCA, ACQ, and copper azole.

The benefits of pressure-treated plywood:

Treated to resist mold, decay, termites
Can use lower-cost plywood as the base
Works for ground contact
Often the most economical option

Drawbacks are the chemicals may leach out over time, and the treatment doesn’t prevent moisture damage. Pressure-treated plywood works best when protected by paint or other finishes. Overall, it provides budget-friendly outdoor protection.

Best Practices for Outdoor Plywood Use

Whichever plywood you choose, follow these best practices to maximize its longevity outdoors:

Use high-quality exterior wood glue when joining pieces
Seal all edges and cut ends with varnish or paint
Allow for drainage and ventilation behind the cabinet
Add finish coats to all surfaces for protection
Inspect annually for any cracks or finish breakdown
Clean off dirt and debris to prevent buildup
Replace deteriorated boards as soon as possible

Even the most weather-resistant plywood requires proper installation and maintenance to perform well outside long-term. Combine good construction practices with a quality outdoor plywood, and your cabinets can last for decades.

Outdoor Cabinet Plywood Recommendations

Here are some examples of recommended plywood grades and types for specific outdoor cabinet applications:

Patio Cabinetry

For typical painted cabinetry on a covered patio or under an awning, go with 5/8″ CDX exterior-grade plywood. The cheaper softwood core helps offset the fact that it’s protected from direct rain and sun.

Garden Storage Cabinet

Use 3/4″ AB marine plywood, which will withstand moisture from damp soil and garden tools stored inside. The thicker boards will resist dents and impact damage.

Backyard Kitchen Cabinets

Choose exterior-grade oak veneer plywood for best appearance, stiffness, and ability to handle outdoor grilling splatters and spills. Go with 1/2″ or 3/4″ thickness depending on cabinet construction.

Mudroom Lockers

Given the potential for wet, muddy clothes storage, use 3/4″ pressure-treated plywood. The preservative chemicals will prevent mold and rot issues in the damp enclosed space.

Poolside Cabanas

For luxury decorative cabinets in full sun and moisture, use 1/2″ teak veneer plywood. The durable tropical hardwood will resist warping and hold up for decades outdoors.

The Bottom Line

When selecting plywood for outdoor cabinetry, the most critical performance aspects are decay and moisture resistance. Marine plywood represents the gold standard, while other exterior and treated plywood alternatives provide good durability at lower cost. Compare material properties and your project requirements to choose the ideal plywood. With proper finishing and maintenance, you can rely on exterior-grade plywood to deliver lasting quality and enjoyment for your outdoor living space.

What Are the Different Grades of Plywood?

Plywood consists of thin layers of wood veneers glued together in alternating perpendicular grains. The quality of the wood veneers used determines the grade of the plywood. There are a few key grading systems for classifying plywood based on the durability and appearance of the wood. Understanding these plywood grades helps ensure you choose the right product for your specific needs.

Grading for Exterior and Marine Plywood

Exterior and marine plywood designed for outdoor and wet use are graded using a simple letter stamp system by the Engineered Wood Association:

A Grade – Top quality veneers without knots or defects on the face or back. Used where appearance is important.
B Grade – Solid face veneers with only minor knots and defects allowed. Serviceable appearance for painting or hidden uses.
C Grade – Lower quality veneers with knots and defects permitted. For utility purposes where appearance does not matter.
D Grade – Lowest grade with coarse veneers full of defects. Only for temporary structures.

The second letter indicates the glue bond quality:

X – Indicates exposure 1 exterior glues used. Withstands moisture and weather.
M (Marine) – Denotes waterproof marine adhesives. Highest moisture resistance.

So “CDX” plywood has economical C-grade veneers with exterior moisture-resistant glue. While “AB Marine” plywood has attractive B-grade veneers and fully waterproof marine glue.

Hardwood Plywood Grading Rules

Decorative hardwood plywood for furniture and interiors follow grading standards established by the National Hardwood Lumber Association (NHLA). The main categories are:

A Grade

Top-level furniture grade
No visible defects
Most aesthetically pleasing

B Grade

Solid appearance grade
Very minor defects blended in
Allows small knots and blemishes

C Grade

Economy grade
Permits some knotholes and repair
Used where appearance less important

Within these categories, there are subclasses from 1 to 3. A1 is the highest quality down through C3 being the most rustic grade allowing large knots and character markings.

Softwood Plywood Rating

Softwood plywood uses a similar grading system for construction applications from the American Plywood Association:

N – Highest quality with tight knot-free veneers
A – Solid surface veneers, tight knots allowed
B – Sound knots and defects permitted
C – Loosen knots, knotholes and repairs acceptable

The lowest D grade allows any visible defect since appearance is not a concern.

Understanding Plywood Grades

For any plywood project, match the grade to your usage and budget:

Top grades like A1 or N provide blemish-free decorative appearance where the wood will be visible – like fine furniture or cabinet doors. The highest quality comes at a premium price.
Middle grades like B or A allow some minor defects while still giving a good surface for painting, trimming, and hidden uses. This provides a compromise on cost versus appearance.
Lower C and D grades work for structural utility panels hidden behind finishes or in temporary structures. The cost savings comes from using more knotty, imperfect veneers with fills and patches.

Always check the specific grading rules for the plywood you’re purchasing, as they can vary. While higher grades look nicer, even low-grade plywood can be perfectly suitable when used strategically so defects are not visible. Knowing the grading language helps match the right plywood to your project requirements.

How Thick Should Plywood Be for Outdoor Use?

Choosing the proper thickness is key to getting maximum performance from exterior plywood. The thickness affects strength, durability, weight, cost, and how the plywood can be utilized. Evaluating your project needs and characteristics of each thickness will ensure you select the right thickness for outdoor plywood projects.

Here is an overview of common plywood thicknesses used outdoors and their benefits:

1/4″ Plywood

Extremely lightweight and thin
Best for delicate cabinet backs, drawer bottoms, and wrapping
Prone to warping if not braced properly
Low cost but least durable option

1/4 inch plywood is too thin for most exterior applications beyond lightweight cabinet components and cladding. The minimal thickness provides very little structural strength or ability to withstand damage.

1/2″ Plywood

Lightweight yet stronger than 1/4”
Suitable for cabinet boxes, shelving, paneling
Still at risk for sagging without adequate supports
Cost effective for many outdoor projects

At half an inch thick, plywood gains significantly more rigidity and construction utility for cabinets, doors, and furniture while remaining lightweight.

5/8″ Plywood

A good compromise of strength versus weight
Enough thickness for cabinet doors, side panels, shelving
Holds fasteners well and resists bowing or cupping
Commonly used thickness for exterior applications

With adequate stiffness at lower cost than 3/4″, 5/8″ plywood covers many outdoor siding, fencing, and construction needs.

3/4″ Plywood

The standard for structural applications
Ideal for decking, fencing, flooring, and outdoor furniture
Provides sheer strength to resist damage
Heavier and more expensive but great durability

At three-quarters of an inch thick, plywood is at full utility strength for robust outdoor projects that need to withstand wear and the elements.

1″ + Thick Plywood

Reserved for heavy-duty structural uses
Prevents sagging spans in decking or shelving
Withstands heavy impacts; resists warping and checking
Much heavier and bulkier to work with

Once you move past one inch thick, plywood takes on a structural slab strength fitting for major permanent constructions and marine builds.

Thickness Recommendations

As a general guideline for exterior projects:

Cabinet doors, lightweight cladding, and wrapping: 1/4″ to 1/2″
Cabinet boxes, furniture, siding, and fencing: 1/2″ to 5/8”
Decking, flooring, shelving, and work tables: 3/4″ to 1”

Consider the expected wear plus structural spans and loading. Thicker plywood brings greater strength, so size up accordingly for heavy-duty outdoor uses. Factor in plywood weight during handling and installation. And remember thickness impacts cost. Find the ideal balance of performance and value for your specific outdoor plywood needs.

How to Finish and Seal the Edges of Outdoor Plywood

Exposed plywood edges present a major vulnerability to moisture damage outside. Taking steps to properly seal the sides, and even back face, are just as important as protecting the front surface. Follow some simple methods to finish off outdoor plywood edges for better weather resistance:

Option 1: Apply Exterior Varnish

Wiping or brushing on a polyurethane varnish coat to the plywood edges creates a durable moisture barrier. Use a fast-drying exterior-grade polyurethane formulated for wood. Thin the first coat 25% with mineral spirits for deeper penetration into the plywood edge. Allow thorough drying between multiple coats for best protection.

Option 2: Use Exterior Wood Filler

Specialized edge fillers and coatings are made to seal porous plywood edges. These are thickened epoxy or urethane formulas that can be squeezed from a tube and smoothed on with a plastic spreader. They quickly fill exposed wood grain and create a tough edge seal.

Option 3: Adhere Edge Banding

For a seamless look, apply thin veneer or PVC edging strips. Use exterior-rated hot melt glue and an edge banding iron to bond the edging material over all plywood edges. Trim excess and the result is attractive sealed edges.

Option 4: Paint the Edges

A primer undercoat followed by one or two topcoats of exterior-grade acrylic latex paint will effectively seal the plywood perimeter. Use a small foam brush and paint just the edge surfaces. Allow each coat to fully dry first.

Option 5: Use Melamine/Phenolic Edge Banding

These extremely dense paper or plastic veneers can be ironed on for the toughest bond. The material is utterly waterproof and provides maximum edge protection even underwater. Common for marine plywood use.

Option 6: Edge Putty Pads

Small dense foam pads can be adhered into inside corners. They compress when the plywood is assembled to seal both edges where they meet. A quick way to block moisture ingress through butt joints.

No matter how you finish plywood edges, be sure to inspect periodically for wear and reapply more sealer if needed. Taking steps to guard vulnerable plywood edges will help your outdoor projects last season after season.

How to Paint Outdoor Plywood Cabinets

Painting is the easiest way to seal and protect outdoor plywood while adding color. Follow these best practices for getting a long-lasting painted finish on plywood cabinets used outside:

1. Choose Exterior Acrylic Latex Paint

Acrylic latex paint stands up to sun, rain, and temperature extremes better than ordinary indoor paints. Look for exterior grade paint with “100% acrylic” on the label. Oil-based alkyd paint also works but requires more cleanup.

2. Remove Grease and Grime

Clean plywood thoroughly before painting to remove surface contaminants. Wipe down with a degreaser and/or lightly sand to degloss and rough up the surface. This promotes paint adhesion.

3. Seal Raw Wood

On fresh bare plywood, first apply an oil-based exterior primer. This penetrates and seals the wood, preventing moisture from bleeding through the finish.

4. Patch Imperfections

Fill any knots, cracks, or holes with exterior wood filler formulated for painted finishes. Let dry completely.

5. Sand Between Coats

Lightly sand glossy surfaces and between paint coats with 220 grit paper

What Plywood is Best for Outdoor Cabinets?