- When your deck is new, you have many choices for protective finishes. Ideally, protective finishes should add beauty to your deck while protecting it from the elements. Varnish is the one sealant This Old House experts warn against for outdoor decking, as it is considered too difficult to maintain. Paints are an option, but will flake and peel over time, requiring more frequent reapplication.
Semitransparent stains are a better choice, providing lasting beauty and protection, while showing off the wood grain. Mark Knaebe, chemist and deck finish specialist for the U.S. Department of Agriculture Forest Products Laboratory, told This Old House that oil-based finishes are best for outdoor decking. Knaebe advises against waiting the traditional nine to 12 months before applying the first protective coat on your new deck. Apply the first coat of stain immediately, then follow up with the second coat in a year. Apply stain in 50-degree F weather or warmer, and always begin from the railing cap, working down the rails to the deck surface when applying. Don't forget the exposed end grain of the wood as well as any wooden structural components. - Contractor Stephen Bonesteel for This Old House suggests that in the spring, when pollen spores are flying and the sticky residue threatens to provide welcome nourishment for mildew, you should give the deck a good scrub. Using a wide-headed utility broom, pour soapy water all over the deck surface and scrub back and forth along the grain of the wood. Rinse the deck well. Allow the wood to dry thoroughly.
- Even with the most dedicated upkeep routine, you will need to refinish the deck every three to four years. This is due to the expected standard wear of the finish originally applied to the deck. The first step after clearing the deck is to wash the surface with a pressure washer or garden hose. Pressure washers are ideal for removing ground-in dirt from wood grain, but take care to avoid stripping the wood. For redwood decks, This Old House experts suggest using a special restorer to get rid of stains around the heads of nails or screws. While still wet, scrub the deck with a chemical-safe brush dipped in cleaning solution. Work with the grain of the wood in small sections from the railing down to the deck surface. Wait at least 15 minutes before rinsing the deck. After your freshly washed deck is completely dry, apply a new stain to protect the surface.