How to stain a deck

Key Takeaways:

• Applying a deck stain helps protect the wood from the elements and makes it last longer.

• There is a difference between a deck seal and a stain, and what you choose depends on your preferred look and level of maintenance commitment.

• Applying a seal or stain to rotting or wet wood is the top reason why finishes fail and peel.

• Staining a deck is a multi-day process and is best done during a stretch of warm, sunny weather.

If you have a wooden deck or balcony on your property, it’s important to give it a proper finish. Not only does this improve the look of the wood and protect it from the elements, it also helps prevent structural damage like rot. 

But applying a deck stain isn’t always straightforward, and an incorrect application can lead to peeling. The key is in proper prep; if the wood is wet or dirty, or if the wrong product is applied over an existing one, the finish likely won’t take. Timing and weather also play a role – it’s best to avoid rain, extreme heat, and humidity while staining a deck.

If this sounds complicated, not to worry; two Toronto-area Pros walked us through their deck staining process: Ivan of Supreno Landscaping, and the team at Veles Construction .

Note: These tips are for softwood decks, such as pressure-treated pine, cedar, and redwood. Dense tropical hardwoods like ipe and cumaru (also known as Brazilian teak) reject ordinary deck finishes and need a specialty product.

Should I seal or stain my deck, and how solid a stain should I use?

Deck stain and seal aren't the same thing, and the one you choose will determine your workload for years.

The difference lies in the colour and opacity of the product, and what they do.

A deck seal is clear; it waterproofs the wood but adds almost no colour, so the wood still greys in the sun.

A stain, on the other hand, adds pigment. This helps block UV and prevents fading; the more pigment there is, the more protection it provides. Stains provide the longest-lasting results, but  they hide the original grain of the wood and once you pick one, it’s tough to change the colour and finish later.

According to the Pros at Veles Construction, the decision is simple: pick a seal for your deck if you like the colour it already is (cedar is a classic option here), and go for a stain if you want to change it. 

Both Pro teams say they steer homeowners away from solid stains, which are the heaviest, most paint-like options. They’re long lasting, but are the toughest products to remove. 

Instead, they both prefer a penetrating oil for the finish, such as Woodluxe oil-based stain and sealer from Benjamin Moore. This soaks into the wood and wears away gradually instead of peeling, so recoating down the road is far less work. 

Above all, one rule of thumb: Don't put a new product over an incompatible old one, such as an oil over a solid film. This is a top cause of peeling. Always check the can's technical data sheet before you buy and apply.

Before you commit to any product, test it on the actual deck. The can lid and a sample board aren’t always accurate, and your wood's species and age can shift the result. Do a small patch in a hidden spot and let it fully dry before starting the rest of the project.

What's the best weather for staining a deck?

Staining a deck is a multi-day job once drying and curing are factored in, so don't start on a whim. Veles Construction recommends planning the job around a warm, dry stretch of weather – preferably five days – with no rain, and a few hours of sun hitting the deck each day.

Both Pros are firm on one thing: never combine the wash and finishing steps on the same day. Ivan from Supreno Landscaping power washes the wood, then waits at least a day to a day and a half – usually two – before anything goes on. 

And you don't want blazing sun during application either. It flash-dries the surface before the finish can soak in, which causes lap marks and stops penetration. The best conditions are warm and dry, not sizzling summer heat.

How do I clean a deck before staining it?

Cleaning the deck before staining is a vital step; rushing this is one of the top reasons finishes fail early. After all, a finish that’s bonded to a grey, weathered surface layer will just lift off with that layer.

Clear the deck, then wash off any grey weathered wood, mildew, and dirt, rinsing well and including the gaps between boards. Use a brightener or neutralizer if your cleaner calls for it.

Pressure washing can be an option in some instances, but homeowners should be cautious. Ivan says that in the wrong circumstances, it can do the most damage; using too much pressure or the wrong nozzle can gouge and fur up softwood, which will prevent the surface from taking stain evenly. Instead, he soft washes, which is a light, low-pressure clean, rather than blasting. 

Not knowing how to run a pressure washer is reason enough to hire a Pro, because incorrect use causes damage fast and shows through the finish.

How do I repair my deck and check it for rot before refinishing it?

No amount of stain can improve a deck that’s not in sound condition. Before applying anything, be sure to drive in or replace any popped screws, and swap out boards that are cracked or cupped.

You can check areas for rot with a feel test: a board that feels soft, spongy, or crumbling is a giveaway. Rot is often structural, so don't sand it or seal over it. In these cases. Determine whether the deck is worth refinishing, or if it requires more extensive repairs, before you invest your time and money on a stain product. 

Do I need to sand my deck before staining?

According to the Pros, it really depends; the age and overall condition of the wood is a big factor here.

Ivan does a light sand after washing to leave a smooth finish on older wood, but brand new boards just get a gentle wash and a coat.

Veles Construction says they sand to solve two specific problems: raised wood grain (which is when moisture makes the grain stand up and feel rough underfoot) and the mill glaze that comes on fresh boards. The grit used depends on the product, with roughly 80 to 120 for a coarse surface, and finishing up around 150 for a premium finish, always sanding with the grain.

It’s also important to avoid over-sanding, which can close up the wood's pores so it rejects the finish. If the surface already feels smooth and the grain isn't standing up, you may not need to sand at all.

How do I know if my deck is dry enough to stain?

The single most common cause of peeling is finish applied to wet wood, whether from rain, the wash you just did, or brand-new lumber that hasn't dried out.

Both Pros judge readiness by experience; they wait rather than rush, and Ivan keeps a moisture reader on hand to check before he starts. If the wood still reads wet, the brush doesn't touch it.

New pressure-treated wood is its own case. It comes loaded with a wet fungal treatment, and you can't finish it until that's dried out. Veles Construction puts this timeline at roughly three to six months, and even longer if the boards were still soaked when they were treated. Because of this, a brand-new deck needs to wait months, not days, before it can be finished with a deck stain.

How do I apply deck stain properly?

Two mistakes give decks the worst finish: applying too much, and letting the edge dry.

When too much deck stain is applied, the penetrating finish only absorbs so much. Anything extra sits on top, remaining tacky, and will eventually fail. To avoid this, wipe the surplus off after a set period of time when using penetrating products. Ivan works one board at a time, spreading the oil out right away rather than pooling it, and back-brushes to work it in. He applies it by brush, not with a sprayer.

However, Veles Construction says the most common homeowner error is using too little product. Starving the brush and repeatedly going over the same spot can lead to each pass drying, especially in warm weather. This can inadvertently build up several thin coats, causing an uneven look. They recommend loading the brush properly, covering the wood, and wiping the excess.

To avoid lap marks (the dark streaks that occur when fresh stain is layered over an already-drying coat), keep a wet edge; always work into a finish that's still wet, and never into a section that's started to dry, following the grain the full length of each board. Where two areas have to meet, Veles Construction feathers the edge out thin rather than stopping hard, so the next section blends in instead of leaving a line. And remember: plan your exit so you're not stranded in a corner, waiting for stain to dry.

How long does deck stain need to cure before I can use it?

Just because your deck is dry to the touch doesn’t mean it’s fully cured; the amount of cure and recoat time will be stated on the product can. Until then keep people, furniture, and animals off the deck and, above all, keep it dry; rain during curing can spot or streak the whole job. 

What are the most common deck staining mistakes?

According to our Pros, nearly every deck staining callback they get comes down to the same two issues: a stain applied over wet wood, or using the wrong product, such as a water-based stain over an old oil-based one.

Over-applying, working in the hot sun, rushing the cleaning process, and skipping the colour test are also common culprits; but none of them are about skill with a brush. Ultimately, staining a deck successfully – the first time – comes down to good, old-fashioned patience.