How to Refinish a Pressure-Treated Deck

Most decks are built using pressure-treated wood because this type of wood has been treated to prevent decay as a result of weather exposure. When building a new deck out of pressure-treated wood, you typically have to wait a certain amount of time for the wood to dehydrate before you can stain and seal it. However, if you are refinishing the wood, you can treat this project exactly as you would any other wood-refinishing project.

Pressure-treated wood can be refinished like any other wood.

Step 1

Sand your deck with an orbital sander to remove the old finish. Start with an 80- to 100-grit sanding pad and sand until the wood is bare. Sweep away the dust, then sand the deck again with a 180- to 220-grit sanding pad. Use a handheld sander for vertical and narrow surfaces, such as the railings and steps.

Step 2

Sweep away the dust from the sanding process. Scrub the deck clean with a solution of 1 cup of trisodium phosphate mixed with 4 gallons of hot water. Rinse the deck thoroughly and allow it to dry for 24 hours.

Step 3

Apply exterior wood stain with a roller or paint sprayer. Use a brush or rag for staining narrow surfaces. As you work, have a partner wipe up the excess stain with a clean cloth. When staining and wiping, always work with the grain of the wood. Allow the stain to dry.

Step 4

Apply an exterior polyurethane sealer to the stained wood. Use a lamb's wool or foam applicator to apply the polyurethane — this type of tool will not leave brush marks in the finish. Allow the polyurethane to dry.

Step 5

Buff the surface of the polyurethane with a 400-grit sanding pad. You only need to scuff the surface slightly to help the subsequent coats of polyurethane bond to the hardened coats — do not sand the polyurethane away. Wipe the deck down with a damp cloth after sanding. Apply up to five coats of polyurethane.