How to Waterproof Plywood – 3 Effective Methods

Plywood is an incredibly popular construction material because of its durability, reliability, and versatility. Whether you talk about interior woodwork, exterior woodwork, commercial, industrial, or domestic settings, you will find plywood everywhere.

With the incredible and wide application of the construction material in question, waterproofing becomes important. Since plywood is made of wood veneer, it can get damaged with extended exposure to water. However, there are ways to make this material repel water. In this article, let us see how to waterproof plywood effectively.

Types of Waterproof Plywood

If you’ve been reading and working with plywood for some time, you must already know about waterproof plywood. These plywood types are not actually waterproof but are mixed with or coating with certain materials, allowing them to resist water.

MR Grade Plywood

MR Grade Plywood is perfect for interior use since this wood is more or less moisture resistant. Even though this plywood is not waterproof, it can sustain considerable exposure to water and moisture. It is treated with moisture and humidity, resisting resins such as formaldehyde, allowing it to be good for places such as offices where there might be humidity but not actual water.

BWR Grade Plywood

BWR Grade Plywood is perfect for both interior and exterior use. Since this plywood is treated with phenolic resins, it can completely resist water. In fact, BWR stands for ‘boiling water resistant’. This plywood is sure to keep looking as good as new even when heavy rain constantly pours on it.

BWP Grade Plywood

BWP or Marine plywood is completely waterproof. This plywood is impervious to moisture and water, allowing it to be very flexible in application. The reason for its waterproof application is the undiluted resin treatment. This plywood can be submerged into water for about three days and still possess the same look and strength.

Should You Waterproof Plywood by Yourself

Plywood waterproofing methods can be expensive and extensive. Therefore, before you indulge in any of the methods, it is best to know if the place you want to use the plywood requires water resistance or not. Moreover, you need to see whether water resistance will be enough or if you’ll need the plywood to be altogether waterproof.

In most cases, the water-resistance or waterproofing grade you’re looking for will be available in the market. However, if you have some simple plywood lying in the house, or if you’re looking to cut down on expenses, you can attempt waterproofing plywood by yourself.

If you decide to waterproof plywood at home, you can even check if the place you’re going to use the plywood is pest-prone. In that case, you can apply a coat of anti-fungal preservative to get maximum protection.

Different Ways of How to Waterproof Plywood

When you set to the task of learning about how to waterproof plywood, you’ll find a lot of methods to do so. Most of the methods include adding a waterproofing material over the plywood to protect it from water and moisture.

Most of the waterproofing materials are available in pain-on or spray-on application bottles. The materials are generally inclusive of liquid latex that can be coated on the construction material when it is wet. When this material dries, it forms a protective moisture-resistant or waterproof layer on plywood.

You can also use various oils and sealers to keep the water from touching the plywood’s water-vulnerable surface. Let us look at some of the most popular methods of waterproofing plywood.

  • Spray-on liquid latex
  • Paint latex waterproofing material
  • Penetrating oils
  • Epoxy sealers
  • Plastic sheets

Epoxy Sealing Method

Epoxy is one of the most common methods you will come across when you’re looking for how to waterproof plywood. The sealant is great to be used on plywood since it does not retain its color over the material. Therefore, after application, the surface will look the same as before but will be water-resistant.

Another reason why Epoxy is commonly used for water-sealing plywood is because of its natural strengthening properties. Therefore, epoxy allows the plywood to be perfect to be used both indoors and outdoors.

Below are the steps you should follow to apply epoxy to your plywood:

  • Clean the surface and remove all the debris, dirt, and loose particles.
  • Read the epoxy sealant’s instructions to dissolve and prepare it for application.
  • Apply the sealant on the plywood with a thick painter’s brush in a thick and consistent layer.
  • The epoxy will dry quickly when it meets the plywood’s surface.
  • Allow the layer to harden and dry before touching it.

In comparison to other waterproofing methods, epoxy is a much stronger and durable method. Therefore, your plywood will be able to take much more water for a longer time at ease. Another great thing about the epoxy application is that you can reapply it to reinforcement without affecting the way the plywood looks.

Penetrating Oil Method

While epoxy is popular for providing complete waterproof properties to plywood, oil tends to make the surface water-resistant. Therefore, if the surface only has to tolerate spills and leakages for a short duration, the oil should be good to go. Otherwise, the layer will give out and allow the plywood to soak water.

Penetrating hard oil functions in a similar way as water. Just as water soaks inside plywood to damage it, oil soaks inside the plywood to keep water from penetrating the surface. Most penetrative oils are made for specific woods. Therefore, we recommend using the oil best suited for your plywood type.

When penetrating, oil-coated plywood types are not perfect for outdoor use. However, with frequent reapplication, you can try using plywood just about anywhere. The only problem with that is the method can become extremely time-consuming and expensive.

Paint or Spray-On Latex

If you’re looking for how to waterproof plywood on a budget, you will come across the paint method. Painting liquid latex on plywood is undoubtedly the most cost-effective method to make plywood waterproof. This method is also quite durable. Moreover, since the spray-on method is so easy, anyone can do it at home without issues.

When you apply liquid latex on surfaces, you seal the porous layer and disallow the water from going inside the surface. Most latex sprays and paints require multiple coating depending on the sealant’s strength and the plywood’s water exposure. However, two to three layers are generally enough.

One of the nicest things about liquid latex paints is how well it decorates the plywood for outdoor use. This method is perfect for layers that get direct exposure to harmful elements. Since the method is versatile, durable, inexpensive, and effective, it is perfect for your deck and beachside balcony.

Wrapping Up

Waterproofing plywood is not a very complex topic. With only a few methods and techniques, you can make any plywood completely waterproof. However, you can also find some plywood types that are waterproof in the first place itself.

Materials such as liquid latex, oil, and epoxy are the most common methods of protecting your plywood against moisture and water. You can choose the method best suiting all your requirements and apply plywood to just about any place without the fear of losing the material and its longevity.

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