How to Make Your Deck Last an Extra 10 Years
A study in Forest Products Journal says wooden decks can deteriorate considerably in just two to three years. That means sooner or later, you’ll need to refinish your deck. Pressure-treated deck lumber is hardy stuff thanks to chemical preservatives forced into the wood fibers, but routine care will extend its service by at least 50 percent. With upkeep, your 20-year deck will last 30 years or more. Plus, the maintenance will save you from having to rebuild your neglected, structurally-compromised deck from scratch.
When you refinish a deck, you’re restoring the barrier that protects it from water and UV radiation, and slowing the aging process. Outdoor variables like sunlight, rainfall, and humidity all age your wood in debilitating ways. Horizontal planks collect dirt and mildew, and sunlight washes their color to gray. Humidity and snowfall shrink and swell planks, leading to fissures, a raised grain, and splinters. Such flaws aren’t just unattractive; they’re potentially dangerous—ill-kept wood is more likely to give way underfoot. But if you haven’t kept up, you can start now.
Refinishing comes down to two stages of work: cleaning and coating. If your current deck already has an old stain, you’ll have to strip that down first. Prepwork introduces some workload variability, but from start to finish, you can expect to put in 1.5 to 3 hours of labor per 100-square feet of deck. (Of course, you can cut those numbers in half if you have a helper.)
The deck we’re refinishing here is of unknown age. Though it’s structurally sound, it’s safe to say it hasn’t been well maintained. Here’s how we refinished it, plus a couple extra steps you might want to use on your own deck.
Fix the structural damage
If you have any broken, rotten, or otherwise unsafe boards in your deck, pry them loose and cut new planks to fill the gaps. If you’ve already purchased your deck finish, it’s wise to apply a coat to the bottoms and end grains of the new lumber before nailing or screwing them into place. This step isn’t critical, since the bottom and sides won’t be subject to standing water. But it will improve long-term water-resistance for the sides you won’t have easy access to in the future.
Our deck is ground level, so there’s no risk of anybody falling through, but we still decided to swap out a few planks that were warped and ugly.
Afterward, walk the deck with a hammer or drill to drive elevated nails and screwheads flush with the wood. You’ll be happy you did this later on, when you start sanding.
Strip down the existing treatment
If you see remnants of an old stain, you’ll need to strip it off before you apply a new coat. Luckily, we were able to skip this step. Our deck hasn’t been treated in years, if ever.
Before purchasing stain stripper (and cleaner and stain, for that matter) you’ll need to take some rough measurements to determine the size of your deck. Ours is an unusual project—two sets of stairs leading down to the yard, plus a sundeck that connects them—that works out to about 1,300 square feet. We’ll use that number to estimate our product needs.
If we were removing an old stain, we’d use Flood Wood Series Pro Stripper. As you’ll see in steps three and four, we’re using all Flood products. You’ll see the best results by sticking with one brand for all your materials, since each component is developed for compatibility with the rest of the product line. Flood, an Ohio-based company, has a long history of specializing in wood care. Since each gallon of our stripper covers 100 to 125 square feet—a figure that’s fairly standard across brands—we would need about 12 gallons for our project.
Before applying any chemicals, clean your deck with a broom or leaf blower, and then wet nearby vegetation with a hose to dilute any runoff. Alternatively, you can protect plants and shrubs by covering them with a tarp or plastic drop cloth.
Follow the directions on your product’s label for guidance, but for Flood’s, you can apply it with a brush, roller, or pump-style garden sprayer. Let it sit for 20 to 30 minutes, scrub it with a synthetic-bristle deck brush, then rinse it clean with a hose or pressure washer with a broad-fan tip. (You do have enough hose to reach every part of your deck, right?)
Although we didn’t have a previous finish to remove, we decided to give our deck a pass with a pressure washer anyway. Unlike a broom or leaf blower, which remove surface debris, pressurized water can scrape away the oxidized patina that forms on lumber over time. That will allow the chemical cleaner, which we’ll apply in step three, to penetrate better.
Morning, evening, or cool days are the best times to pressure wash, since rapid drying can cause excessive splintering. Unless you’re experienced with the wand, it’s best to stick to a relatively low-pressure washer—ideally below 2,000 psi. More than that and you’re likely to etch the wood.
Hold the wand’s nozzle about a foot from the deck and move it side-to-side in a smooth, consistent motion. You’re looking to see cleaner, brighter wood without inflicting damage, and you may need to back off or move closer to achieve that happy medium. With my 1,800-psi washer, 10 inches felt about right.
As you clean, blast the space between deck boards, too. Excessive debris buildup can inhibit drainage.
Wash with deck cleaner
Now you’re ready to apply a chemical cleaner to remove deep-embedded oil that could block stain from entering the wood fibers. Refer to the label on how much to buy, but in general, a gallon of cleaner will cover anywhere from 150 to 350 square feet. For our 1,300-square foot deck, we used 5 gallons of Flood’s bleach-based Pro Series Wood Cleaner. (If our deck was in better shape we'd use the All-Purpose Wash.)
Cheaper cleaners, which are often little more than detergents, require scrubbing, while those with oxalic acid or bleach, like Flood’s, do the hard work chemically: You just apply and rinse. Given the size of our project, we were happy to take the easier route.
We covered the deck with Wood Cleaner using a plastic, pump-style garden sprayer. Then we let it sit for about 10 minutes and rinsed it clean with a garden hose. Again, you may want to wet or cover nearby vegetation before working with chemicals.
Work in small, manageable sections to ensure a uniform cleaning process. We’d thoroughly wet about a dozen planks with Wood Cleaner and then hose them all down before moving on.
Sand, stain and seal the wood
After cleaning your deck and before applying the finish, wait two or three rain-free days for the wood to dry: Stain won’t penetrate damp wood. Check the weather forecast, too, to ensure at least two more dry days after you apply your stain or sealant, to let it set completely.
Old wood is likely to have splinters and loose wood fibers that can interfere with the sealant’s penetration, so sand your deck just prior to applying the treatment. We used a pole sander and 100-grit sandpaper, but if you have the back for it (or a smaller deck) a belt sander will do a better job.
Move in the direction of the wood’s grain, and if you’ve put down any new lumber, sand that, too. You want to remove the tough layer of mill glaze that forms when the plank is cut.
The big decision you need to make when choosing your sealant is how much color you want. On one end of the spectrum, you have a clear finish. Despite the name, it does contain subtle pigmentation to help with UV protection. This is a great option for newer decks with healthy looking wood.
On the other end of the spectrum, you have solid-colored stains. Avoid these. The coloring is the result of finely ground oxides and other suspended solids that thicken the finish, and as a result, they make it less likely to absorb completely into wood. Solid stains end up forming a surface-level film similar to what you’d expect with paint, and that’s a problem: Once moisture breaks through, it can do damage from the inside. On hot, sunny days, water trapped between the wood and the film will turn into vapor, apply outward pressure, and cause the stain to chip or peel.
For our deck, we opted for the middle ground, semi-transparent. It penetrates the wood enough to protect it from moisture and sunlight, but it also provides a decent color upgrade, which will impart a touch of youth.
Use masking tape or paper to protect surfaces you don’t want stained, such as your house or a concrete landing. Then follow the sealant’s instructions for mixing. To save yourself a sore shoulder, you may want the help of a heavy-duty cordless drill attached to a mixing paddle, used at a low speed to avoid splattering.
Sealant requires several hours to work into the wood, so it’s best to avoid applying it under a hot, mid-day sun, which could lead to partial evaporation. Mornings and evenings are ideal. Use a brush for the tight spots around spindles and between boards, and for broad surfaces, use a garden sprayer, paint pad, or thick-nap roller. If you do use a pad or roller, make sure you have replacements handy. Over time, the soft surfaces collect splinters and will stop spreading as well. For our job, we ran through three paint pads.
As you work, maintain what painters call a “wet edge,” which is where you avoid letting the area you’re working on dry out. If you find yourself painting over dried spots, you’ll end up with patchy lines of light and dark coloring. With a wet edge, you ensure a uniform stain.
Then leave the deck alone for about 24 hours. In extremely hot, arid conditions, the stain might be fully set by the time you’ve taken a lunch break and cleaned up your work. But cooler weather, humidity, and shade from clouds and trees can all slow the drying time. So to avoid scarring your work with discolored spots, wait a full day before sliding the grill and patio furniture back into place.
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