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How to Waterproof Plywood

How to Waterproof Plywood

Many craftworkers use plywood in construction work. Plywood is several layers of veneer that are laid perpendicular to the previous layer, pass through a press, and are then ready for use. The veneer production technology is very simple, so we use this material in many areas.

The cost of plywood is low, so it is also often used in repair work. This shows that the range of applications for this material is really wide and varied. We can use it in finishing works. Plywood can level the ceiling, use it as a backing for flooring. We often make lightweight building structures of plywood, we make partitions in buildings.

With so many advantages, plywood has one big and significant drawback. Under the influence of water and moisture, plywood quickly loses its original appearance, becomes brittle, deformed, and exfoliates. And then the question arises. How can you make the plywood last much longer even when exposed to moisture? This is the question we tried to answer in our article.

Protection methods

How to treat plywood from water? There are many ways to carry out protection:

Epoxy compound layer

One method to improve the strength and moisture resistance of plywood is to use epoxy. This method is widespread in production, and many workers know about it. After treatment with epoxy resin, plywood becomes hard, durable. When moisture gets in, plywood does not absorb water and therefore remains strong and unharmed.

This method has a small drawback. Epoxy resin is the strongest allergen. We recommend using plywood with such a coating only in utility or technical areas. There are special solutions that reduce the concentration of epoxy resin. It reduces both the exposure to allergens and the strength of the material. Dilution of epoxy with such solutions is also a very complex and time-consuming process. Professionals should only do this. Also, to dry plywood, you will need a construction hair dryer, which is expensive. Therefore, this method is not suitable for every owner.

Using acrylic varnish

Such a product does not have a pungent, poisonous odor; moreover, unlike oil varnishes (plywood oil), it perfectly impregnates surfaces.

Parquet varnish covering

The next method that we will talk about is available to everyone. Using parquet varnish, you can significantly strengthen the plywood and make it moisture resistant.

There is a wide selection of paints and varnishes in stores, so when choosing a varnish for covering a plywood sheet, pay attention to the following:

  • Polyurethane varnishes will make the plywood durable;
  • Nitro lacquers are quick-drying, moisture-resistant and hard enough.

Before opening the plywood with varnish, it must be sanded with sandpaper. After that, the plywood needs to be wiped, primed, and degreased. After the primer has dried, apply the varnish of your choice to the surface and leave it to dry. It is better to apply varnish in several layers, so the plywood will be even stronger.

The use of fiberglass

This method is costly and laborious, but it can get a good moisture resistance effect and strengthen the material. For you to succeed, you need to perform the following manipulations. Prepare a sheet of plywood. To do this, duplicate everything that we told in the previous paragraph. After the varnish dries, glue gauze or a sheet of fiberglass to the plywood and open the plywood with another coat of varnish. Leave the plywood for 3-5 days until it is completely dry. After that, apply the last coat of varnish, let it dry and you can use the plywood for construction work.


Using this method, you must glue the plywood with plastic, metal, or special film sheets. To make the plywood strong using this method, you will need to apply the resin to the plywood sheet. After that, put a sheet of plywood on it with a sheet of metal or plastic and press two materials. After that, the ends of the plywood sheet are treated with protective compounds and we can use it in work. This method is not suitable for home use.

Use of paints

The last method we will tell you about is the use of paint coating. When choosing paint, take one that has water-repellent properties. The paint should not allow moisture to pass through. This method is not expensive and can be easily done at home. When using plywood in residential areas, it is best to use water-based paint. Such paint dries quickly, does not have allergic components, and plywood painted with such paint can be further used in the house.

How to paint? When painting outdoors, ready-made diluted enamels can be used. This will save you time. You will not need to prepare the paint, come up with the proportions to dilute the enamel, and so on. You just take a paintbrush and paint and start painting the plywood sheet.

First, the material should be carefully sanded with sandpaper. Then use a brush or roller to coat the surface with a primer. Let the primer dry. After 3-4 hours, be able to apply the first coat of paint. Leave the paint to dry, and after completely dry, apply another coat of paint.

Post-treatment of plywood to maintain moisture protection

Sometimes plywood can become a cheap material during the renovation. Plywood can partition for walls and even be used for flooring. If, during operation, the plywood sheet cracked or cracked on it, then after while moisture will get there and the sheet will completely exfoliate. At such moments, one cannot hesitate. You need to reinforce the chips and cracks. To do this, use putty. Take sandpaper, clean the cracks well. Treat with a primer and putty. You can still open such places with lag, paint, or epoxy.

Using plywood as flooring

We can use plywood sheets as a backing for expensive flooring materials. Sometimes plywood is used to make rough, test floors, and sometimes as the primary material for flooring.

If you have chosen plywood as a floor covering, then you should think about how to make it durable, protect it from the sun and moisture. First, you need to sand the surface, then coat with acrylic primer and dry the plywood sheets for about three days. This coating will protect the plywood from the effects of mold and mildew. If, after several years of operation, you notice cracks appearing on the plywood, then it’s time to update the protective coating.

Application of additional materials

What other materials can strengthen the plywood sheet:

  • Polymer primers. Penetrates deep into the plywood layer and strengthens it from the inside;
  • Putty for woodworking. Used for leveling the surface, removes chips, cracks, and deformation of the plywood sheet;
  • Varnish. We recommend using it after applying a coat of paint. Used to cover plywood on walls and floors;
  • It treats the surface with sticky sandpaper;

These were additional tips when working with plywood to help you protect it from moisture and sun exposure.

Useful Video: Polyurethane Plywood Deck Coating

Final Words

Lightweight and cheap to use, the material can deteriorate from high temperatures and high humidity. Carefully selected means of strengthening the top layer of plywood will contribute to its durability and increase its wear resistance.

Plywood is a wood material that can delight you with its aesthetics and attractive price. If you find chips, crayons, or large cracks on the plywood, do not get upset and run to the building materials store for new sheets. Ahead of you is a minor repair using one of the suggested methods above. If you follow these manipulations, then the plywood will serve you for over one year.