How to Stain a Deck

Walk the deck first and deal with structure before appearance. Probe the joists and the ledger with a screwdriver, especially where the deck attaches to the house — that connection is where deck failures happen, and a rotted ledger is not a staining problem. Replace split or cupped boards and set any protruding fasteners below the surface.

New pressure-treated lumber needs to weather before it will take a stain. Fresh treated boards are still wet from the treatment process, and a finish applied too early sits on top and peels. Sprinkle water on the boards: if it beads and sits, the wood is not ready; if it soaks in within a few seconds, it is.

Clean with a deck cleaner rather than plain water. Mildew, pollen, and the grey oxidized surface layer all block penetration. If there is an old failing finish, it has to come off with a stripper — a new coat over a peeling one peels with it.

Pressure washing works if you are disciplined about it. Keep the pressure low, use a fan tip, hold it well off the surface, and keep it moving with the grain. Too much pressure raises the grain and etches soft summer wood, which leaves a fuzzy surface that drinks stain unevenly and looks blotchy no matter what you do next.

After cleaning, let the deck dry fully. Two clear days is a reasonable minimum here, longer after a heavy wash or in a shaded, low-airflow spot.

Transparent and semi-transparent stains penetrate the wood and wear away gradually rather than peeling. They show the grain, need recoating more often, and are far more forgiving to maintain because there is no failing film to strip.

Solid stain is closer to paint. It covers grain and weathered colour differences, which is why it gets used on older decks, but it forms a film — and films peel when moisture gets underneath. Once a deck has been coated solid, it generally stays that way.

Oil-based products penetrate well on horizontal surfaces that take direct sun. Water-based products clean up easier and hold colour longer. Either can work; what does not work is layering one type over a different type without stripping first.

Work in shade, or follow the shade around the deck through the day. Stain applied to hot boards flashes off before it penetrates and leaves lap marks.

Coat two or three boards at a time and run the full length of each board without stopping in the middle. Stopping mid-board is what creates a visible line. A stain pad or a brush gets more product into the wood than a roller; if you spray, back-brush immediately.

Do the railings, balusters, and stair treads before the deck field so drips land on unfinished wood. Wipe any excess that has not soaked in after about fifteen minutes, particularly with penetrating stains — pooled stain stays tacky and collects dirt.

Check the forecast for 24 to 48 hours out, not just the afternoon. A surprise evening thunderstorm on a fresh finish means starting over.

Sweep leaves and pine needles off through the fall instead of letting them mat down over winter; that mat holds moisture against the boards and is where rot and mildew start. Keep planters on feet rather than flat on the deck for the same reason.

Expect to refresh a penetrating stain every two to three years on sun-exposed surfaces and less often on shaded or covered sections. A light clean and recoat on schedule is a fraction of the work of stripping a neglected deck back to bare wood.