Deck stain guide

The five tiers

Deck stains run on one axis: how much pigment. More pigment means more UV protection and a longer interval, and less visible grain. The trade at the far end is not just looks — it changes how the finish fails.

New wood, and how to know it is ready

Freshly bought pressure-treated lumber is usually still wet with treatment. Stain applied to wood that cannot absorb it sits on the surface, dries unevenly and lifts. That is the single commonest reason a new deck's finish looks bad within a year.

Ignore the calendar and use the water test: sprinkle water on the boards. If it beads and sits, the wood is not ready. If it soaks in within a minute or so, it will take stain. Test in several places — the middle of the deck dries faster than the shaded edge, and one end of a board can pass while the other fails.

Kiln-dried-after-treatment stock, and naturally durable species like cedar, are usually ready much sooner. Cedar has its own catch: mill glaze, a burnished surface from the planer that repels finish. A light sanding or a brightener opens it up.

Prep is the whole job

Every finish failure that is not "too wet" is "not clean". Stain bonds to wood, not to the grey, dead surface layer, not to mill glaze, and certainly not to the last coat's remains.

1. 01Sweep and clear. Furniture off, debris out of the gaps between boards — a stiff putty knife pulls the packed leaf litter that holds water.
2. 02Clean. A deck cleaner appropriate to the wood, worked in and rinsed thoroughly. Greyed wood usually also wants a brightener afterwards to restore the pH and the colour.
3. 03Strip, if there is a failing film. A peeling solid stain has to come off. This is the reason the film tiers cost more in labour over time.
4. 04Sand where needed. Raised grain, splinters, mill glaze. Not the whole deck unless it needs it — over-sanding closes the pores and the stain will not penetrate.
5. 05Fix the wood. Reset popped fasteners, replace anything soft. Staining over a rotten board buys nothing.
6. 06Let it dry. Fully. Washing and staining in the same day is the second commonest failure after staining new wood.

Applying it

Pick the weather, not the weekend. Out of direct sun, well inside the product's temperature range, and with dry weather after — most failures on a well-prepped deck are rain landing on a finish that had not cured.

Work board by board, end to end. Stopping mid-board leaves a lap mark that will not sand out. Two or three boards at a time keeps a wet edge across the run.

Do not over-apply. Penetrating stain takes what the wood absorbs; anything left on the surface stays tacky and collects dirt. Back-brush what a pad or sprayer leaves, and wipe standing excess.

Stir, and box the cans. Pigment settles, and two cans of the same colour are not identical. Mixing them together before you start prevents a visible line halfway across the deck.

Do the edges and ends. Board ends drink water and are where rot starts. Get stain into them, and into the railing undersides nobody sees. Work out your gallons first with the stain calculator — running out mid-deck forces exactly the lap mark you were avoiding.

What fails first, and when

Not the whole deck at once. Horizontal surfaces in full sun go first — the deck floor and the top of the rail cap take the UV and hold the water. Vertical faces, risers and shaded areas can look fine for years longer.

That means maintenance is not a whole-deck event on a fixed schedule. Watch the sunniest stretch of floor; when water stops beading there and the colour has gone flat, clean and recoat that area. On a penetrating finish, a maintenance coat on the worn zone blends in — which is exactly why penetrating finishes are easier to live with.

The recoat interval is a property of the product and your climate, and the label is the authority. A deck under trees in a wet climate is a different job from one in high desert sun, and no interval printed in a guide covers both.