To stain a deck well, wait until the wood is dry enough to absorb finish, clean it, and apply a penetrating stain in thin, even coats, working along full board lengths. Then recoat before it wears through. For quantity, most deck stains cover roughly 150 to 300 sq ft per gallon. Measure the deck floor, stairs and railings separately, because railings often add more surface than people expect.
The rest of this guide covers each step in the order you would do it, with a worked estimate at the end.
Step 1: Decide whether the wood is ready
New pressure-treated lumber often arrives wet from treatment. Stain will not soak into wood that is already full of water, and a finish applied too early tends to sit on the surface and fail.
How long to wait depends on the product and the climate:
- Sherwin-Williams advises waiting at least 6 months before staining pressure-treated wood so it is fully dry.
- The USDA Forest Products Laboratory notes that decking with a factory-applied water repellent may not absorb a semitransparent stain at first. It suggests letting such wood weather for 2 to 3 months before finishing. It also warns that waiting much longer can lead to significant checking.
Kiln-dried-after-treatment (KDAT) lumber and naturally durable woods like cedar are usually ready sooner. Always follow the label on the stain you buy.
The sprinkle test. Flick some water onto several boards, including ones in shade. If it beads up and sits on the surface, the wood is not ready, or an old water-repellent finish is still active. If it darkens the wood and soaks in within a few minutes, the wood will take stain. Test again the morning you plan to work.
Step 2: Clean the surface
Stain bonds to clean wood fibers. Dirt, mildew, pollen and old flaking finish all cause blotching and early failure.
A practical cleaning sequence:
- Sweep and clear the gaps. Use a putty knife or gap tool to push debris out from between boards so water can drain. The deck board spacing guide explains why those gaps matter.
- Apply a deck cleaner. Commercial deck cleaners and brighteners remove mildew and dirt without adding color, according to the Forest Products Laboratory. For mildew, the FPL describes household bleach diluted with 3 parts water plus some detergent. It cautions never to use a detergent containing ammonia, since ammonia and bleach form a toxic gas.
- Scrub gently and rinse. The FPL warns that aggressive scrubbing with a caustic cleaner or power washing can remove wood from the surface, particularly on soft woods such as western redcedar. If you use a pressure washer, keep the pressure low, use a wide fan tip, and keep the wand moving with the grain.
- Let it dry. The FPL recommends allowing at least 2 warm, windy days of drying after cleaning before finishing. Sherwin-Williams similarly advises waiting 24 to 48 hours after rain.
Fix the boards before you finish them
Cleaning shows problems you could not see under dirt. Before staining:
- Set or replace any screw heads or nails that have backed out.
- Sand raised grain and splinters, especially on stair treads and the handrail.
- Replace badly cracked or soft boards now. Matching new wood after staining is harder.
Step 3: Choose the right type of finish
Deck finishes fall into two families, and the difference affects how the deck ages.
Penetrating finishes soak into the wood and do not form a surface film. This group includes water-repellent preservatives, lightly tinted toners, and semitransparent stains. The Forest Products Laboratory’s guidance is direct: “penetrating finishes, not film-forming finishes, should be used on wood decks.” Oil-based semitransparent stains “will not blister or peel even if excessive moisture enters the wood,” and their pigment protects the surface from sunlight.
Film-forming finishes include solid-color stains and paint. They hide grain and can cover mismatched boards. But the FPL notes they are prone to trap moisture, wear through underfoot, and fail by peeling, which makes recoating harder because you have to remove the loose film first.
Here is how the main options compare, using the FPL’s descriptions:
| Finish | Look | Durability on decking | Recoating |
|---|---|---|---|
| Clear water-repellent preservative | Natural wood, no color | About 1 year on exposed deck surfaces | Easiest, no stripping |
| Tinted toner / colored WRP | Light color, grain clearly visible | Longer than clear, depending on traffic | Easy |
| Semitransparent stain | Noticeable color, grain still visible | Pigment greatly increases durability | Clean and recoat |
| Solid-color stain or paint | Opaque, grain hidden | Wears and peels on walking surfaces | Often needs stripping or sanding |
A useful middle path from the same FPL bulletin: use a penetrating stain on the floor and stairs, and if you want an opaque look, put solid stain or paint only on the railings. Railings don’t take foot traffic, and the FPL says paints and solid-color stains “may perform quite well” there.
Composite and PVC decking generally do not need stain. If yours has faded, check the manufacturer’s care guide before applying anything. See decking materials compared for how maintenance differs by material.
Step 4: Apply the stain
Good technique matters more than brand:
- Watch the weather. Pick a dry stretch with no rain forecast for at least a day, and stay within the temperature range on the label. Avoid staining in direct midday sun on hot days, because stain flashes dry and leaves lap marks.
- Do the railings and stairs first, then the floor. Drips from railings land on unstained boards, where the floor coat will cover them.
- Work two or three boards at a time along their full length. The FPL explains that lap marks form when fresh stain overlaps an area that has already dried, which leaves a stripe with two coats. Finish each board to an end or a butt joint before moving on.
- Back-brush. Whether you start with a pad, roller or sprayer, brush the stain into the grain and pick up any puddles. Excess stain that sits on the surface can turn tacky or peel.
- Coat the end grain. Board ends and cut ends absorb the most water. Give them an extra pass.
- Second coat: follow the label. Some penetrating stains call for a second coat while the first is still wet. Others need a full day between coats, and Sherwin-Williams’ general guidance is to wait 24 hours between applications.
Step 5: Estimate how much stain to buy
Stain coverage varies with the product, the wood species, and how weathered the wood is. Rough, new or heavily weathered softwood drinks more than smooth, previously finished boards.
Published ranges for reference:
- Most deck stains cover between 150 and 300 sq ft per gallon for a first coat, and adding about 10% for spills and waste is a common allowance.
- Sherwin-Williams cites about 250 to 350 sq ft per gallon, depending on wood type.
Use the coverage printed on your product’s label when you have it. Plan on the low end of the range for the first coat on new or weathered wood.
Worked example
A 12 × 16 ft deck with a 4 ft wide stair (4 risers, 3 treads) and 40 linear feet of 2x2 baluster railing:
- Deck floor: 12 × 16 = 192 sq ft. The deck square footage calculator handles L-shapes and cut corners, and the square footage guide explains the method.
- Stair treads: 3 treads × 4 ft × 0.92 ft (11”) = about 11 sq ft.
- Risers and stringer faces: 4 risers × 4 ft × 0.625 ft (7-1/2”) = 10 sq ft, plus a few square feet for the outside stringers. Call it 13 sq ft.
- Railing: a 2x2 baluster is 1-1/2” wide on four faces. At roughly 33” tall, that is about 1.4 sq ft per baluster. At about 2.4 balusters per foot (3-1/2” gaps), that comes to about 3.3 sq ft per linear foot. Add rails, cap and posts and you reach about 4 sq ft per foot. 40 ft × 4 = 160 sq ft.
Total: 192 + 11 + 13 + 160 = 376 sq ft.
At 175 sq ft per gallon for a first coat on new pine, that is 376 ÷ 175 = 2.15 gallons. A second coat usually goes further, since the wood is partly sealed. Assume 250 sq ft per gallon, or about 1.5 gallons. Add 10% and the job needs about 4 gallons.
Note that the railing in this example takes almost as much stain as the deck floor. Estimates that use only the floor area run short.
The deck stain calculator does this math, with separate inputs for stairs, railings, coats and coverage. Buy all the stain at once and mix the cans together (called boxing) so the color stays consistent across the deck.
How often to restain
Floor boards and stair treads wear fastest because they get foot traffic and direct sun. Sherwin-Williams suggests restaining every 2 to 3 years depending on climate and wear. Clear water repellents need it more often.
A good cue is the sprinkle test again. When water stops beading on the most exposed boards, clean and recoat before the wood turns gray and starts to check. The Forest Products Laboratory notes that most decks are retired because of cracks and checks that timely finishing could have largely prevented.
Frequently asked questions
How long should I wait to stain a new pressure-treated deck?
It depends on how wet the lumber was and the product you use. Sherwin-Williams recommends at least 6 months for pressure-treated wood. The Forest Products Laboratory suggests 2 to 3 months of weathering for decking with a factory water repellent. Use the sprinkle test: if water still beads, wait longer.
Is it better to use oil-based or water-based deck stain?
The Forest Products Laboratory notes that wood resists waterborne penetration and that waterborne formulas are more likely to form a thin film, while oil-based semitransparent stains absorb without forming one. Water-based products dry faster and clean up with water. Either can work if you follow the label and the wood is properly prepared.
How many gallons of stain do I need for a 12 x 16 deck?
The floor alone is 192 sq ft, which at 150 to 300 sq ft per gallon is roughly 0.6 to 1.3 gallons per coat. Stairs and railings can nearly double the total surface, so a full 12 × 16 deck with railings and two coats often needs 3 to 4 gallons. Measure your railings rather than guessing.
Should I stain or seal a deck?
A clear water-repellent sealer keeps out water but has no pigment to block sunlight, so the wood still grays. The FPL puts its service life at about a year on exposed deck surfaces. A semitransparent stain adds pigment, which the FPL says greatly increases durability. Many products are sold as a “stain and sealer” because they combine color with water repellency, so check the label.