Decks need to be cleaned and sealed regularly to keep them looking great and protecting the wood from moisture damage. A good sealant repels water, preserves the wood with a mildewcide, and screens out harmful UV rays.

Apply the sealant with a brush, roller or sprayer, working in a well-ventilated area. Be sure to choose a dry, cool day to work; the sun can cause the sealant to evaporate too quickly.

Preparation

The first step in the deck staining and sealing process is to remove any loose debris with a broom or power washer. Be sure to follow the directions on the cleaning product you choose and keep the nozzle at least 8- to 12-inches away from the wood to avoid damage.

After cleaning, let the deck dry completely before proceeding to sanding. You can use a hand-held sander or a pole sander to speed up the process and ensure that it’s done evenly. Start at one end and work your way across the deck, always sanding in the direction of the grain. Be sure to wear a dust mask to avoid breathing in sawdust. Check out deck cleaning for more information!

If possible, try to perform this step in the morning when it’s cool and not windy. Sunlight can cause the sealant to evaporate too quickly, preventing it from soaking into the wood properly. This is especially important if you live in a sunny climate zone.

Cleaning

A wood deck that isn’t protected with a stain or sealant will eventually develop a gray, weathered appearance. A regular cleaning and refinishing schedule will help protect the structure from decay and keep it looking new.

Before beginning a deep clean, hose down the surface to loosen dirt and grime. If you have a pressure washer, a jet setting will quickly power away caked-on dirt. Be sure to cover nearby plants with tarps, and choose a cloudy day for applying your cleaner to avoid inadvertently damaging the landscaping.

Begin by scrubbing the deck with your scrub brush in the direction of the wood grain. Use a stiff bristle brush for any stubborn stains and concentrate on areas that are heavily soiled or stained. Most deck cleaners must be left on the deck for the amount of time recommended by the manufacturer. After the product dries, rinse the deck thoroughly with a garden hose.

Staining

When the deck is clean and dry, apply a wood stain. Use a paint brush, sprayer, or pad applicator and a large drop cloth to protect surrounding areas. If you use a sprayer, place a sheet of heavy-weight canvas over the spray area (rather than plastic) so it won’t blow away.

Stain in long, smooth strokes that cover two to three boards at a time. If you’re using a solid stain, apply the first coat in thin layers to avoid puddles that don’t soak into the wood. You can also choose to apply a semi-transparent stain or a clear sealer.

Be sure to read the product label and Technical Data Sheet, or SDS, for safety instructions. Also, be aware that the wood will need a full day to dry after applying the stain. The best time to work is in the morning before sun set. Avoid working on older decks made from lumber pressure-treated with chromated copper arsenate, as this can release toxic arsenic into the soil and air.

Sealing

Wood decks must be regularly sealed to protect them from moisture damage. Moisture causes cracking, warping and rot in wood. Sealing keeps water and sun’s damaging UV rays from soaking into the deck, extending its lifespan.

Before applying the sealant, sand the deck to smooth its surface and remove any mold or mildew. This prepares the deck for the sealant and ensures its proper adhesion to the wood.

After sanding, make sure the deck is dry and free of dust or dirt. Then follow the product’s application instructions for a brush, paint roller or sprayer. Generally, the best method is to apply a thin coat that covers two-to-three boards at a time.

Protect nearby plants and shrubs by covering them with plastic or tarps to avoid the potential of damage from runoff or overspray. Once the deck is thoroughly dried, it can be used as usual. If you are unsure how often your deck should be sealed, consult the manufacturer’s recommendations for your specific region.