Not all decks are constructed of pressure treated timbers, many are surfaced with plywood. Plywood is created by layering thin wooden boards that are compressed and glued together with the wood grains opposing one another. Waterproofing plywood preparation is the first step in preserving any plywood decking project during installation. Waterproofing is essential for both plywood that has been installed as indoor flooring and as outside decking. Sealing the substrate prevents moisture damage that can lead to:
- Curling or peeling away of adhered surface materials such as with linoleum or paint.
Plywood is a common choice of materials for a substrate. As a flooring or decking surface material, plywood is versatile, economical and easy to work with. Using the right construction and finishing methods, plywood substrates become durable and long-lasting. For the best results in waterproofing a plywood deck, start with the right preparation techniques.
Steps for Properly Waterproofing Plywood
#1. Waterproofing Plywood: Inspect It before
- Thoroughly inspect every inch of the substrate for soundness and quality.
- Repair or replace as necessary.
- Confirm that substrate is securely fastened to supports.
- Inspect cracks of seams carefully. Use a putty knife to pry out any debris.
- Cover seams with flashing paper then caulk edges and seams.
#2. Waterproofing Plywood: Drains & Openings
Plywood deck that has a drain it should be constructed of galvanized or stainless steel and be properly flanged. Cast iron or plastic are unsuitable drain materials. Do not use shower drains in decking systems as they are not designed for this use. When a copper drain is installed special care must be taken to avoid contact between dissimilar metals that can cause rust and corrosion.
#3. Prepare The Surface
- Remove contaminants that might interfere with the adhesion of the sealant such as paint or oil.
- Use a broom and give the surface a thorough sweeping to remove debris and dirt.
- Use a stiff bristled push-broom to scrub the substrate vigorously. Remove any debris that is on the surface.
- Sweep again and make certain that the plywood is completely dry.
#4. Waterproofing Plywood: Apply Primer
Apply a single layer of base coat. The first coat will penetrate into the substrate. When it cures it will strengthen the plywood from the inside out. It creates the conditions for the sealant to adhere permanently to the surface of the plywood.
#5. Waterproofing Plywood: Patch & Prepare
After the base coat has completely dried, inspect the substrate once again. Patch any cracks, holes, joints or seams with a rubberized base mixture. It’s consistency should be similar to that of caulk. If any rough areas are present, smooth them out with a coating of the same mixture. Caulk all junctions where the substrate meets a wall.
#6. Waterproofing Plywood: Apply The Membrane
Once caulking and patches are dry, it is time to apply the rubberized membrane that will completely waterproof the plywood surface.
#7. Waterproofing Plywood: Finishing Touches
After the sealant has cured, complete the final finishing. The plywood surface should be painted or texturized according to personal preference.
#8. Waterproofing Plywood: The Top Coat
When the final finish has cured, one last top coat seals the entire project. This will add a final layer of protection to a plywood deck that is easy to clean, seamless, slip resistant and, best of all, waterproof.
How To Get Yours
Plywood substrates are very popular with DIY enthusiasts, as well as designers on a budget. It is also commonly found throughout homes and commercial structures. The most important thing to do in order to get the most out of this building material is to use professional products and apply them with the methods professionals advice. The temptation to take a shortcut may arise. Don’t do it.
The best products on the market, such as the PLI-DEK waterproofing deck system, have been developed over years of professional laboratory testing and research. To achieve the results the product promises, as well as retain the benefit of a manufacturer warranty, it is important to follow manufacturer application instructions. For more information on sealant products and the best techniques of application, please contact us.