If you have ever wondered whether you can use plywood outdoors, the answer is Yes. Different types of exterior plywood can be used outdoors for shelving, decking, subflooring, and even for boats.
DIY home-owners also use exterior plywood for outdoor furniture, planters, sheds, benches and even gazebos.
Exterior plywood is designed to withstand outdoor conditions and has an ability to resist moisture and water exposure. It is mainly manufactured using water-resistant adhesives such as phenolic or WBP (Water Boil Proof) glue, enabling it to withstand humidity, rain, and other moisture sources.
Besides, the glue and preservatives used in exterior plywood provides protection against rot, fungal growth and decay. This is strengthened by the use of high-quality hardwood or softwood veneers which contribute to overall stability and durability.
What type of plywood is best for outdoor use?
Among the various types of exterior plywood, the best for outdoors use is marine grade plywood.
Marine grade plywood, often referred to as marine plywood or marine-grade ply, is a high-quality type of exterior plywood specifically designed for use in marine environments and other outdoor applications with high moisture exposure.
It is considered the best exterior plywood for outdoor use, particularly in projects where water contact is a concern.
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Here’s why marine grade plywood stands out.
Why marine grade plywood is best for outdoors:
Waterproof Adhesive:
Marine grade plywood is manufactured using a waterproof adhesive, typically phenolic or WBP (Water Boil Proof) glue.
This adhesive provides exceptional bonding strength and prevents water from seeping into the layers of the plywood, making it highly resistant to delamination and decay caused by moisture.
Boiling Water Test:
Marine plywood undergoes a stringent “boiling water test” during manufacturing.
This involves boiling the plywood samples in water to ensure their ability to withstand exposure to moisture without losing strength or structural integrity.
High-Quality Veneers:
Marine grade plywood is constructed using high-quality hardwood veneers that are carefully selected for their uniformity, strength, and resistance to moisture and decay.
These top-grade veneers contribute to the plywood’s superior performance and longevity.
Rot and Fungal Resistance:
The waterproof adhesive and high-quality veneers used in marine plywood make it highly resistant to rot, decay, and fungal growth, even in harsh outdoor conditions.
Outdoor applications for marine-grade plywood
1.Marine Environments:
As the name suggests, marine grade plywood is widely used in boat-building and marine applications.
It is specifically engineered to withstand the challenges posed by constant exposure to saltwater, making it the ideal choice for constructing boat hulls, decks, bulkheads, and other marine components.
2.Docks and Piers:
Marine plywood is also suitable for constructing docks, piers, and other waterfront structures that are subject to frequent water exposure.
3.Outdoor Furniture:
Marine grade plywood is often used in outdoor furniture construction, where it provides excellent durability and moisture resistance, ensuring the furniture withstands various weather conditions.
4.Decks and Outdoor Flooring:
Marine plywood can be used in outdoor decking and flooring projects, especially in areas where the deck is subject to occasional water splashes or high humidity.
5.Exterior Facades and Cladding:
Marine plywood can be utilized in exterior facades and cladding, where its resistance to moisture and weather ensures the longevity and appearance of the building.
Pros & Cons of Marine-grade plywood:
Pros:
- Marine-grade plywood has an exceptional resistance to water and resistance.
- It is highly durable and remains in good shape for extended period outdoors.
- Water-resistant properties enhance ability to withstand rot and water damage.
- It is engineered to be strong and stable.
- It is a versatile material adaptable to various outdoor projects.
Cons
- Marine-grade plywood has higher cost compared to other types of plywood.
- It is also heavier due to its denser construction and higher-quality veneers.
- Limited availability-It might not be as readily available as other exterior plywood
Other types of exterior plywood:
Depending on the type of outdoor project that you have, here are some other exterior plywood that you might consider:
Pressure-Treated Plywood:
Pressure-treated plywood is infused with chemicals to make it more resistant to decay and insects. It undergoes a pressure treatment process, which forces preservatives deep into the wood fibers, enhancing its durability and longevity.
This type of plywood is commonly used for outdoor decks, fences, and other structures exposed to the elements.
Structural Plywood:
For projects that require both strength and weather resistance, structural plywood is a good option.
This type of plywood is designed to carry heavy loads and withstand various weather conditions, making it suitable for outdoor construction like roofs, subfloors, and exterior walls.
Overlay Plywood:
Overlay plywood is specifically engineered for projects that require a smooth, paintable surface.
It is often used for outdoor furniture, cabinetry, and decorative elements, providing an attractive finish while maintaining weather resistance.
Aircraft Grade Plywood:
While commonly used in aviation, aircraft-grade plywood can also find applications in certain outdoor projects.
It is made using high-quality veneers and adhesives, offering excellent strength and moisture resistance. However, it can be relatively expensive and may not be as readily available as other types.
Shuttering Plywood:
Shuttering plywood, also known as film-faced plywood, is designed for temporary outdoor applications such as concrete formwork.
 It features a smooth, phenolic film coating on both sides, providing enhanced resistance to moisture and wear.
Difference between marine-grade plywood and standard plywood.
Marine-grade plywood and standard plywood differ significantly in their construction, adhesive, and intended use. The main distinctions between the two types of plywood are:
- Adhesive:
- Marine-Grade Plywood: Uses a waterproof adhesive, typically phenolic or WBP (Water Boil Proof) glue, providing excellent water resistance and preventing delamination in wet conditions.
- Standard Plywood: Uses various types of adhesives, such as urea formaldehyde or melamine, which offer limited water resistance and are not suitable for prolonged exposure to moisture.
- Moisture Resistance:
- Marine-Grade Plywood: Offers superior moisture resistance and can withstand direct and prolonged contact with water without deteriorating.
- Standard Plywood: Provides only limited moisture resistance and is more susceptible to damage from water exposure.
- Intended Use:
- Marine-Grade Plywood: Primarily designed for marine environments, boat-building, and outdoor projects with high moisture exposure.
- Standard Plywood: Generally used for interior applications, furniture, cabinetry, and other projects where moisture resistance is not a critical factor.
- Quality of Veneers:
- Marine-Grade Plywood: Utilizes high-quality hardwood veneers carefully selected for their strength and resistance to moisture and decay.
- Standard Plywood: May use lower-grade veneers that are more economical but lack the same level of durability and resistance to water.
- Durability and Longevity:
- Marine-Grade Plywood: Offers exceptional durability and longevity in outdoor and marine environments, thanks to its waterproof adhesive and high-quality materials.
- Standard Plywood: While durable for indoor use, it may not hold up well in prolonged exposure to outdoor conditions, especially moisture-rich environments.
- Cost:
- Marine-Grade Plywood: Tends to be more expensive than standard plywood due to its higher quality materials and construction.
- Standard Plywood: Generally more budget-friendly and widely available in various grades and thicknesses
| Feature | Marine-Grade Plywood | Standard Plywood |
| Adhesive | Waterproof (phenolic or WBP glue) | Various (urea formaldehyde, melamine) |
| Moisture Resistance | High, excellent for marine and wet environments | Limited, not suitable for prolonged exposure to water |
| Intended Use | Marine environments, boat-building, high moisture projects | Interior applications, furniture, cabinetry |
| Quality of Veneers | High-quality hardwood veneers | May use lower-grade veneers |
| Durability and Longevity | Very durable, long-lasting outdoors | Durable for indoor use, less suitable for extended outdoor exposure |
| Cost | Higher cost | More budget-friendly |
Can you treat regular plywood for outdoor use?
Yes, regular plywood can be treated for outdoor use to some extent. You can use polyurethane, paint or epoxy to waterproof the plywood. Applying a water-resistant sealant or paint on all sides and edges can improve its moisture resistance and make it more suitable for outdoor projects.
However, even with treatment, regular plywood may not match the durability and performance of marine-grade plywood or pressure-treated plywood, which are specifically designed for extended outdoor use and high moisture exposure.
For critical outdoor applications, it is advisable to use marine-grade or pressure-treated plywood to ensure optimal performance and longevity.
For further information, read our guide on how to waterproof plywood.
How long will plywood last in the rain?
The longevity of plywood in the rain depends on various factors such as the type of plywood, quality, treatment, and the intensity of exposure.
Regular plywood left untreated can begin to delaminate and deteriorate within a short time when exposed to consistent rain and moisture, and rot within one to two years. Marine-grade plywood, designed for water resistance, can last significantly longer, with proper sealing and maintenance.
Generally, plywood’s lifespan in the rain can range from a few months to several years, but for extended outdoor use, it’s advisable to choose marine-grade or pressure-treated plywood for enhanced durability and protection against moisture.
Can plywood be weatherproof?
Plywood is generally not weatherproof since it is made of veneers from wood that is also not also weatherproof. However, plywood can be made weather-resistant to some extent through proper treatments and coatings.
Marine-grade plywood, specifically designed for outdoor and marine use, offers superior water resistance and weatherproofing due to its waterproof adhesive and high-quality veneers.
Regular plywood can also be made more weatherproof by applying water-resistant sealants, paints, or varnishes to protect it from moisture and outdoor elements.
However, while these treatments can improve its resistance to weather, plywood may not be completely weatherproof and may not withstand prolonged exposure to harsh weather conditions as effectively as marine-grade or pressure-treated plywood.
