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How to Waterproof Plywood: A Complete Guide

how to waterproof plywood
12 December 2023 1762 view(s)
How to Waterproof Plywood: A Complete Guide

Wondering how to waterproof plywood to protect it from damage? Look no further! This article will walk you through the steps to effectively waterproof plywood.

We'll cover essential aspects such as selecting the appropriate waterproofing products, properly preparing the plywood's surface, expertly applying the waterproofing solution, sealing edges and joints to ensure comprehensive protection, and offering tips on maintaining the waterproofing over time.

Don't let water ruin your plywood - learn how to protect it and keep it safe.

 

Choosing the Right Waterproof Plywood

The first step in knowing how to waterproof plywood is choosing the right waterproofing products for your project. There are a few key factors to consider.

Determine The Plywood

Firstly, you need to determine the type of plywood you're working with. Different types of plywood have different levels of water resistance, so it's essential to choose a waterproofing product, like moisture resistant plywood, that is compatible with the specific type of plywood you have.

Be Aware Of Environmental Conditions

Next, you should consider the environmental conditions that your plywood will be exposed to. If your project is going to be outdoors and subjected to heavy rain or extreme weather conditions, you'll need marine grade plywood that offers maximum protection. Our waterproof plywood is specifically designed to withstand the battles of harsh outdoor conditions.

Isn't All Plywood Waterproof?

While plywood is generally known for its versatility and strength, it's essential to understand that not all plywood is inherently waterproof. The waterproofing capability of plywood depends on various factors, these include:

        1. Type of Adhesive: Plywood is constructed by bonding layers of wood veneers together using adhesives. The type of adhesive used plays a critical role in determining plywood's water resistance.

  • Moisture-Resistant Plywood: This type of plywood is designed with moisture-resistant adhesive, making it suitable for areas with occasional humidity. However, it may not be entirely waterproof and should not be submerged in water.
  • Marine Grade Plywood: Marine plywood is engineered with high-quality, waterproof adhesive that provides excellent resistance to water and moisture. It is ideal for applications where plywood will be exposed to constant or prolonged contact with water, such as boat building and outdoor construction.
     

        2. Surface Finish: In addition to adhesive, the surface of plywood can also affect its resistance to water. Applying waterproof coatings or sealants can enhance the plywood's ability to         withstand moisture.

        3. Treatments: Some plywood products receive additional treatments or coatings during or after manufacturing to improve their waterproof properties. These treatments can significantly enhance plywood's resistance to water.


Not all plywood is waterproof by default. It's essential to select the right type of plywood for your specific project and, if necessary, take steps to waterproof it further using appropriate products and techniques. You can explore our selection at MGM Timber for reliable and high-quality waterproof plywood options.

Consider Ease Of Application

Another important factor to consider is the ease of application. Some waterproofing products require multiple coats or complex application methods, while others can be easily applied with a brush or roller. Consider your level of experience and the time you have available for the project when choosing a product with an application method that suits your needs.

You want a product that will provide long-lasting protection and withstand the test of time. Shop from reliable products like our plywood sheet materials that offer excellent durability and long-lasting quality.

Preparing the Plywood Surface

To properly prepare the plywood surface for waterproofing, start by thoroughly cleaning the plywood to remove any dirt, dust, or debris. Preparation is crucial as it ensures that the waterproofing product adheres properly to the surface and provides effective protection against moisture.

Remove Loose Particles

Begin by sweeping or vacuuming the plywood to remove loose particles. Next, use a mild detergent mixed with water to clean the surface. Scrub the plywood gently using a soft-bristle brush or sponge, paying special attention to any areas that are particularly dirty. Rinse the plywood with clean water and allow it to dry completely before proceeding to the next step.

Address Imperfections & Damage

After cleaning the plywood, it's important to address any imperfections or damage on the surface. Inspect the plywood carefully for any cracks, holes, or rough areas. Use a putty knife to fill in any cracks or holes with a wood filler or putty. Smooth out the surface with sandpaper to ensure a level and even finish. This step not only improves the appearance of the plywood but also helps prevent water from seeping through any gaps in the surface.

Apply Primer

Once the plywood is clean and any imperfections have been addressed, it's ready for waterproofing. Applying a primer before the waterproofing product can further enhance the plywood's resistance to water damage. The primer creates a barrier between the plywood and the waterproofing product, ensuring better adhesion and a longer-lasting finish. Follow the manufacturer's instructions to apply the primer evenly across the entire plywood surface. Allow the primer to dry completely before moving on to the final step of waterproofing the plywood.

Applying Waterproofing Solution

When it comes to sealing outdoor plywood, applying the waterproofing solution is crucial. Various products are available, each with its unique advantages and applications. Here, we'll explore some common products used for waterproofing plywood and provide essential tips for their application:

  1. Epoxy Sealer: Epoxy sealer is an oil-based thick coat that penetrates wood pores, making plywood waterproof from the inside. It effectively blocks out moisture and air infiltration, preventing mould growth.
  2. Varnish: Varnish is a thin resin that creates a hard, protective coating when cured. It enhances the aesthetics of plywood surfaces, giving them a rich, dark brown colour resembling high-quality wood.
  3. Water-Based Paint: Water-based paints can be used to waterproof outdoor plywood. While they provide protection, they may require touch-ups or repainting every few years to maintain effectiveness.
  4. Drying Oil: Drying oil, such as Tung oil, is an excellent choice for outdoor use. It soaks into plywood sheets, providing an effective protective coat while allowing some natural flexibility and moisture retention.
  5. Liquid Latex: Liquid latex is an easy-to-apply option for sealing plywood. It creates a protective layer that seals pores, preventing water infiltration. Liquid latex can be purchased as a spray for small projects or in larger quantities for more extensive jobs.
    When applying these waterproofing solutions, prioritising safety is essential. Many of these products contain toxic substances, so always use Personal Protective Equipment (PPE) to protect your nose, mouth, hands, and eyes during application.

Make sure you have all the necessary materials ready, including a high-quality waterproofing solution, a brush or roller, and a clean container for mixing the solution if required.

Remember to clean your equipment immediately after use, following the instructions provided by the manufacturer. Properly storing the remaining waterproofing solution is also important to ensure its longevity and effectiveness for future use.

Sealing the Edges and Joints

To properly seal the edges and joints of the plywood, start by ensuring that the waterproofing solution is thoroughly applied in these vulnerable areas. The edges and joints are the most susceptible to water damage, so it's crucial to pay extra attention to them during the waterproofing process.

To begin, apply a generous amount of the waterproofing solution along the edges of the plywood. Use a brush or a roller to distribute the solution evenly, making sure it penetrates the wood fibres. This will create a barrier that prevents water from seeping into the plywood through the edges.

Once the edges and joints are coated with the waterproofing solution, allow it to dry completely. This may take a few hours or overnight, depending on the product you're using. Check the manufacturer's instructions for the recommended drying time.

After the solution has dried, inspect the edges and joints for any missed spots or areas that need additional sealing. Apply another coat of the waterproofing solution if necessary, ensuring complete coverage.

Maintaining and Reapplying Waterproofing

To maintain the waterproofing on your plywood, you should regularly reapply the waterproofing solution. Over time, the protective coating on the plywood can wear off, making it susceptible to water damage. By reapplying the waterproofing solution periodically, you can ensure that your plywood remains protected and extends its lifespan.

The frequency of reapplication depends on various factors, such as the type of waterproofing solution used, the weather conditions in your area, and the amount of exposure to moisture. As a general guideline, it's recommended to reapply the waterproofing solution every 1 to 3 years. However, if you notice any signs of water damage or if the plywood is frequently exposed to water, it may be necessary to reapply more frequently.

Before reapplying the waterproofing solution, make sure to clean the plywood surface thoroughly. Remove any dirt, debris, or loose particles using a brush or a vacuum cleaner. For stubborn stains, you can use a mild detergent or a specialised cleaner. Once the surface is clean, allow it to dry completely before applying the waterproofing solution.

Use a brush, roller, or sprayer to evenly apply the solution onto the plywood surface. Pay special attention to the edges and joints, as these areas are more prone to water penetration. Allow the solution to dry completely before exposing the plywood to moisture.

Find The Best Waterproof Plywood At MGM Timber

Knowing how to waterproof plywood effectively involves several key steps to ensure lasting protection. Selecting the right waterproofing products tailored to your plywood type and intended use is a huge step in the right direction.

At MGM Timber, you can find quality marine plywood options designed for various applications, providing peace of mind for your projects.

When it's time to apply the waterproofing solution, follow the manufacturer's instructions carefully and don't forget to seal the edges and joints, as they are particularly susceptible to water damage.

Lastly, remember that maintaining and periodically reapplying waterproofing is essential to prolong the plywood's lifespan and protect it from moisture. Regular cleaning and reapplication, typically every 1 to 3 years, depending on your conditions, will keep your plywood in top shape.

MGM Timber are leading timber merchants in the UK. We offer a range of sheet materials and other timber options to shop from. Our commitment to quality makes us your ideal source for timber solutions. Get in touch with our expert team or personally visit your nearest branch today.

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