How to Seal a Pressure Treated Deck

Clean a deck before applying sealer.

Pressure-treated decks require sealing to keep the wood from eventually rotting from liquid that penetrates the surface. Deck boards are porous and absorb water, swelling the wood and rotting it from within. Over time, the wood becomes soft, cracking under the pressure of foot traffic or heavy items such as grills or furniture. With proper sealing, the deck repels water, allowing it to evaporate on the surface instead of absorbing into the timber.

Things You'll Need

• Plastic tarps
• Garden hose
• Liquid dish soap
• Pump sprayer
• Deck sealer
• Paintbrush

Instructions

1. Remove furniture, grill and potted flowers from the deck. Place plastic tarps over grass or plants next to and under the deck.

2. Wet the deck with a garden hose. Sprinkle two to three drops of mild liquid dish soap onto the wet deck. Sweep the deck with a broom, distributing the soap over the entire deck. Rinse the soap from the deck with the garden hose. Allow the deck to dry completely.

3. Fill a pump sprayer with the deck sealer. Starting at one corner at the back of the deck, spray the deck boards lightly with the sealer. Work your way across the back of the deck. Look for any puddles of sealer as you spray and wipe them with a brush to remove. Continue spraying and moving back and forth until you reach the front of the deck. Spray deck rails and steps with the sealer. Allow the sealer to dry completely.

4. Spray on a second coat of sealer after the deck has dried. Repeat the procedure outlined above, removing puddles as you go.

5. Replace deck furniture and other items after the deck has dried.

Tips & Warnings

• Avoid sealing the deck in direct sunlight. Wait until the area is shaded.

• Wear eye goggles and rubber gloves when applying sealer.

• Seal the deck when temperatures are in the 60s and 70s to keep the sealant from evaporating too quickly.

References

• Lowes: Clean and Seal Your Deck
• Ask the Builder: Wood Deck--Clean/Seal