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How to Waterproof a Plywood Deck

Updated February 21, 2017

Plywood is a versatile construction material used for many projects including building decks. It consists of multiple layers of wood, called plys, compressed and glued tightly together. The interior layers are often softer wood, while the outer layers consist of harder wood. Like all outdoor wood, especially wood on horizontal surfaces, you must waterproof plywood decking to protect it from deterioration. Any standard wood waterproofing product also seals plywood.

Sweep the deck off using a broom to remove all leaves, dirt and debris. Cover all nearby desirable grasses, flowers and shrubs to prevent them from damage.

Fill a bucket with 1 gallon of water and a general household cleaner using the amount specified on the bottle. Insert a long-handled scrub brush into the mixture and clean the entire plywood deck by scrubbing it vigorously. Rinse the plywood off with a garden hose to remove all cleaning residue. Allow the plywood deck to dry overnight until no moisture remains.

Open a can of wood waterproofing liquid and pour some into a paint tray. Insert a paint roller with a long-handled extension into the liquid until it is saturated.

Roll the waterproofing liquid onto the plywood deck in long, even strokes until you've covered and sealed the entire deck.

Allow the sealer to dry for at least 24 hours, longer if specified on the bottle, before walking on it.

Tip

Wood waterproofing products are available in clear or in a tinted stain that alters the colour of the plywood. Plywood decks require waterproofing every two to three years depending on the specific product. When you can splash water onto the deck and it no longer beads up, it is time to apply another coat.

Warning

Do not apply the waterproofing product when you're expecting rain or during a time of the year when leaves or other debris falls from the trees.

Things You'll Need

  • Tarp
  • Broom
  • Bucket
  • Water
  • General cleaner
  • Long-handled scrub brush
  • Garden hose
  • Paint tray
  • Paint roller with handle extension
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About the Author

Kimberly Johnson is a freelance writer whose articles have appeared in various online publications including eHow, Suite101 and Examiner. She has a degree in journalism from the University of Georgia and began writing professionally in 2001.