Which Type of Plywood is Best for Outdoor Use?

Plywood is a composite material made up of thin layers, or plies of wood veneer bonded together with adhesives under high pressure. As plywood has a cross-grain structure, it has more strength than traditional wood. When using plywood outside, the most important selection to make is the right kind of plywood for exposure to moisture, sunlight, and temperature changes.

The plywood for exterior work is treated to resist warping, cracking, and rotting when exposed to moisture.

It is often more affordable than solid wood making it the best for budget-conscious projects.

Plywood can be used in many applications from outdoor furniture to sheds, boats, even house exteriors.

The strength and structural integrity are excellent thanks to the cross-laminated layers.

Marine plywood should be the number one choice for projects exposed to direct contact with moisture, such as docks, boats, and outdoor furniture. Made with waterproof glue and quality hardwood veneers, marine plywood is built to withstand exposure to water without delamination or warping.

Water Resistance: Chemical adhesives used in the marine plywood make it resistant to water.
Few gaps: Marine plywood is manufactured in a way to be least defective with very few gaps so the water does penetrate through.

Exterior-grade plywood is simply known as plywood for outdoor use and is applied in decking, exterior walls, and outdoor furniture. Boiling Water Proof (BWP) and Boiling Water Resistant (BWR) are two grades of plywood in the market. While both are water-resistant, BWP is of better quality with higher water resistance.

Being immune to warping, even when immersed in boiling water continuously for 72 hours, this has become an ideal choice for outdoor applications where there is constant water exposure.

This pressure-treated plywood is infused with chemicals that resist decay, rot, and infestation by insects. It is ideal for full ground contact as well as for humid surroundings. It is generally used as plywood for outside decking, garden structures, and playhouses.

Also known as phenolic plywood, this plywood uses phenolic resin that ensures excellent resistance to moisture and abrasion making it an ideal plywood for exterior applications.

The key features are:

• High Moisture Resistance: The resin offers resistance to moisture penetrations of the plywood and can be used in moist or rainy climates.
• Scratch and Impact Resistance: The same resin also makes the surface resistant to scratches and impacts, thus lengthening its lifespan.
• Rot Resistance: This type of plywood undergoes chemical treatment which resists fungi and insects on the plywood.

Not as water-resistant as BWP, BWR grade should be avoided in areas that are exposed to water.

If the project is exposed to heavy downpour of rain or to high humidity, then opt for marine plywood or BWP-grade exterior plywood which can provide superior resistance to water and is durable despite continuous exposure to moisture.

In the case of load-bearing structures like decking and wall cladding, one would require exceptional strength from the plywood. Marine plywood and BWP-grade plywood are perfect for such applications.

Some outdoor projects like furniture or exteriors, require a smooth finish. Being calibrated, phenolic plywood gives a high-gloss finish with which one can easily paint or stain to get the effect on desires.

Plywood, no matter how tough, will need some measure of protection to be there for a long time outdoors. Here are some tips on protecting your plywood for exterior use:

Seal the plywood with a waterproof sealer or paint to give it added layers of protection against moisture.

Structures made of plywood must not touch soil or any standing water.

Inspect and resurface your plywood outside for any damage due to exposure to the environment.
Selecting the right plywood for outdoor use determines the longevity and success of one's project. Be it furniture, decking, or external construction, choosing the right plywood assures the project remains strong and is able to keep issues at bay. One must carefully evaluate the project needs and level of exposure to water and temperature fluctuations along with factors like budget to choose the right plywood.

Frequently Asked Questions

1. How can one make a decision between MDF and plywood for furniture projects?
In case the project requires structural strength and longevity, like bookshelves or a table, plywood is highly preferred. But in case the furniture serves more as a decorative piece, where smooth finishing counts, one may go for MDF.

2. Which is best suitable for kitchen cabinets-MDF or plywood?
Plywood is preferred for kitchen cabinets because it has better moisture resistance and strength. While MDF is not less resistant to moisture, it should not be applied in areas where water is always present.

3. Will MDF work outdoors?
MDF should not be used outdoors because it is sensitive to moisture, tends to swell or break when it comes into contact with water, and it generally does not perform well when exposed to water. Plywood is often used for outdoor applications, especially marine-grade plywood.