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How do you stain and seal a wood deck?

Updated August 2026

1–2 days including drying · Moderate DIY

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Refinishing a deck is a two-day job on a 2–3 year cycle: clean and rinse on day one, let the boards dry 24–48 hours, then sand the rough spots and coat on day two. The trigger is not the calendar but the water test. Sprinkle a cup on the boards, and if it soaks in and darkens the wood instead of beading, the finish is spent. Coat on a mild, dry day out of direct sun, ideally between 50 and 85 degrees with no rain for 24 hours after, and expect $50–150 in cleaner and stain for a 300-square-foot deck.

What you need

Before you start: Rags and pads soaked in oil-based stain can self-heat in a pile and start a fire, so spread them flat outdoors until stiff or drop them in a sealed metal can of water before they hit the trash. That is the most common way a deck project burns down a garage. Skip the pressure washer unless you have run one on wood before: above 1,500 psi a narrow tip shreds softwood decking and drives water deep into the boards. Wear eye protection with any cleaner containing bleach or sodium hydroxide, and rinse nearby plants before and after.

Steps

  1. Run the water test on three or four spots. Beading means the finish is still working and you can wait a season; soaking in means it is time.
  2. Clear the deck completely and sweep the gaps between boards with a putty knife. Trapped debris holds moisture, and that is where rot starts.
  3. Fix the wood before you touch a finish. Set every proud nail below the surface or replace it with a screw, and probe soft, dark boards with a screwdriver. If the tip sinks a quarter inch, that board gets replaced now rather than stained over.
  4. Brush on the deck cleaner, let it dwell the time on the label (usually 10 to 15 minutes, never letting it dry), scrub with the grain, and rinse well. Follow with brightener on gray wood or after any bleach-based cleaner.
  5. Let the deck dry 24 to 48 hours. Damp wood will not take stain and traps moisture under the film, which is what makes a finish peel six months later.
  6. Sand the traffic lanes and handrails with 60- or 80-grit, then sweep and blow the dust off. Do not go finer: over-sanded wood closes the grain and refuses stain.
  7. Mask the siding, cover the plants, and stir the stain rather than shaking it. Stir again every 15 minutes, because the pigment doing the UV blocking settles to the bottom of the can.
  8. Coat two or three boards at a time, running full board lengths end to end with the pad. That keeps lap marks out of the middle of the deck. Brush the rails and stairs separately and back-brush any puddles.
  9. Follow the can on coats. Most semi-transparent stains want one, film-forming solid stains want two, and anything that has not soaked in after 15 minutes gets wiped off.
  10. Stay off it for 24 hours, and keep furniture and planters off for 48 to 72 hours, longer in humid weather.

Or hire it out

A refinishing crew charges $2–5 per square foot, so $600–1,500 on a 300-square-foot deck, covering the cleaning, sanding, and coats. They work faster and own the sprayer, but the materials are the same $50–150 you would buy. The real money is in what the cycle prevents: replacing rotted decking runs $10–25 per square foot, and a full rebuild starts around $30 per square foot.

Done. Now the part everyone skips: doing it again on schedule. Log it in OnOtto and the next reminder for deck sealing sets itself.

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Frequently asked questions

Sealer or stain: which one does my deck need?

Clear sealer repels water and does almost nothing about UV, so it needs redoing every 1 to 2 years and lets the wood gray anyway. Semi-transparent stain adds pigment, blocks UV, still shows the grain, and holds 2 to 3 years, which is why it is the default recommendation. Solid stain lasts 3 to 5 years but behaves like paint: when it fails it peels, and stripping it later is a weekend you will not enjoy.

How long do I wait to finish a brand-new deck?

Pressure-treated lumber arrives saturated with treatment chemicals and needs to dry before it will absorb anything, typically 2 to 6 months depending on your climate. Skip the calendar and use the water test on a few boards. Cedar and redwood can usually be finished within a few weeks. Either way, get the first coat on within the first season, because unprotected new wood mills and cracks faster than most people expect.

Do I have to strip the old finish first?

Not for semi-transparent stain that has simply worn thin. Clean it, brighten it, and recoat. You do have to strip when the existing finish is solid or film-forming and is peeling, flaking, or blistering, because new stain over loose film fails with it. Stripper runs $30–60 per gallon plus a lot of scrubbing, and it is the argument for staying on schedule rather than waiting five years. Deck resealing intervals has the full timing.

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