If you’ve maintained your deck in warmer months, you might assume this is enough to last throughout colder months. Unfortunately, that assumption could lead to many costly problems throughout the life of your deck.
Deck maintenance during the warm and cool seasons is a good idea to make the most of your investment. Although you might use your deck sparingly in winter, some deterioration could happen. Let’s look at what you can do to protect your deck in winter.
What Happens to Your Deck in the Winter
During the cold months, the deck itself is experiencing transformation, primarily due to moisture trapped in the deck materials that undergoes cycles of freezing and thawing. Trapped moisture can cause wood to warp, crack, and rot. Mix this with the sun’s UV rays and rock salt and ice melt you use to eliminate ice, and you have serious reactions that cause subtle but severe damage.
You might not see anything happening, but beneath the deck’s surface, the structure of your deck can be compromised each winter. This could lead to expensive repairs and decreased lifespan of your deck. Proper TLC in the cooler months can keep your deck in tip-top shape for many years.
Ways to Protect Your Deck in Winter
How do you keep your deck from being destroyed by cold air and winter precipitation? Here are a few deck care tips to follow in winter.
Eliminate leaves and debris
In the fall months, leaves, twigs, pine cones, and dirt easily accumulate on all surfaces, including your deck. These items can absorb moisture and discolor your deck and cause damage if left underneath snow and ice throughout winter. Make sure that you clear any debris using a leaf blower or broom before the first snowfall. Also ensure no leaves are stuck between the boards so that water can drain easily when it rains.
Another good practice is to remove furniture, rugs, mats, and grill from the deck in winter and move them to a garage, basement, or storage shed. While these items aren’t a threat to the deck, the space underneath them could be breeding grounds for mold and mildew.
Check for mold and mildew
Once your deck is cleared off, inspect each surface for the presence of mold or mildew. A combination of humidity, sun, and shade might have aided in growing mold or mildew on your deck, especially underneath the wood planks. Left unchecked over the winter, the problem can worsen, resulting in rotting wood.
To check for mildew or early rot, look for areas where water doesn’t bead up on contact. If you find any, power-wash the deck with a solution of one part bleach, three to five parts water, and laundry soap. For cedar decks, use only oxygenated bleach, which is gentler on softer woods. Let the deck dry thoroughly before applying a new layer of penetrating waterproof finish.
Know the Difference: Mildew and mold require the same treatment, but they look different. Mildew comes in white, brown, or gray and is always flat — rub your hand against it and you’ll see a powdery residue. Mold, on the other hand, has texture to it and comes in many colors, including red, purple, brown, or black. If you rub your hand against mold, you’ll feel a slight raised surface. Black mold is the worst offender, so address it immediately.
Give it a solid cleaning
Before the frost of winter sets in within your city, thoroughly clean your deck. Just as you would clean your deck in spring, you should give it one final cleaning in fall. Use an oxygenated-bleach cleanser (never chlorine bleach) and a soft scrub brush to remove dirt, paying extra attention to any spots that you noticed to have mold, mildew, and algae growth. The cleaner might need to sit for 10 to 15 minutes in order to remove dirt, mold, and mildew. Afterwards, rinse thoroughly with a hose.
While many homeowners reach for a pressure washer, TOH general contractor Tom Silva prefers a simple pump sprayer with a biodegradable wood cleaner mixed with water at a 1-to-1 ratio. As Tom demonstrated on a recent project, a pump sprayer paired with a scrub brush cleans the wood thoroughly without the risk of damaging fibers the way an overpowered pressure washer can. If you do use a pressure washer, fit it with a gentle 40-degree fan nozzle and hold the tip about 18 inches from the wood surface.
When scrubbing, always work in the direction of the wood grain and tackle the deck in small sections, starting from the top rails and working down to the floor. For cedar or redwood decks specifically, stick with a commercial cleaner containing oxygen bleach (sodium percarbonate), which is a gentler mildew-killer than other options. For pressure-treated pine or tropical hardwoods, the USDA’s Forest Products Laboratory recommends a homemade solution that’s strong enough to cut through dirt, mildew, and algae without turning the wood white and fuzzy.
Apply a stain or sealant
Treated wood decks have longer lifespan than untreated ones. So if you have an untreated deck or it’s been more than 2 or 3 years since your last application, now might be an ideal time to apply a stain or sealant to your deck.
One main difference between the two products is that a sealant is clear and a a stain has slight pigmentation or color. No matter which you choose, make sure the product is designed to repel water, preserve the wood with a mildewcide, and screen out UV rays. Applying one of these protections to your deck will allow your deck to last longer and minimize damage caused by ice, snow, and rain.
Before applying stain, make sure your deck is thoroughly dry — three or four consecutive days without rain is typically enough in most climates. If you’re unsure, check with a moisture meter; when it reads 15 percent or less, the wood is ready to coat. When spraying or rolling on a stain, immediately brush the coating afterward to ensure proper adhesion and an even finish. Stir the stain frequently during application for consistent color across all your boards.
Check for pests
You might have a more serious problem than moisture issues if you notice rotting wood. Pests could be present. Termites can eat your wood deck, and carpenter ants can burrow and create nests. Besides these common pests that are attracted to wood, there could also be rats, mice, possums, and raccoons looking for a place to hibernate in winter.
To minimize destruction by pests, inspect your deck for pests in the fall and ensure there aren’t any settling in or under it. Call a pest control company to immediately take care of any problems.
Pro Tip: On a TOH project, pest control expert Bill Siegel stressed the importance of maintaining separation between soil and wood structures: “Pull the soil away so there’s good separation between the wood and the earth. Otherwise, you’re just making a trail for the insects.” When prepping your deck for winter, check that soil, mulch, or leaf buildup hasn’t raised the grade around your deck posts or where the framing meets the ground.
Know the signs: Subterranean termites—the most common type—travel through mud shelter tubes that look like brown rope about the width of a pencil along your foundation and deck framing. Carpenter ants, on the other hand, don’t eat wood but excavate clean, debris-free galleries that follow the softer spring growth in the grain. Look for small holes in the wood surface where ants push out shavings and insect parts. Spotting these telltale differences helps you and your pest control pro determine the right treatment.
Remove snow from your deck
The moisture from snow can threaten a wood deck. Sure, the sun’s UV rays will eventually melt the snow, but this might not happen swiftly enough. Not to mention that accumulated snow and ice on your deck makes it slippery and dangerous for those who need to walk on it.
Instead of waiting for Mother Nature to clear the snow and ice away, it might be better to safely shovel snow using a plastic shovel to prevent scraping the paint, stain or the wood itself. Also be mindful to move the shovel along the length of the boards (not across the width), so as not to leave obvious scratches. An alternative option is to use a snowblower. Or if there is just a light snowfall, you can sweep snow using a broom. It’s not recommended to use ice melt or rock salt on a deck, since they can harm or discolor the finish.
Why to avoid salt-based deicers on decks: Chloride-based ice-melt granules — including rock salt, calcium chloride, and magnesium chloride — can corrode metal fasteners, damage finishes, and harm nearby plants and soil. According to TOH Magazine, these products have “a nasty way of corroding metal, spalling concrete, and fouling waterways and soil, not to mention burning pets’ paws or making them sick.” If you must use a deicer on adjacent walkways, consider an acetate- or formate-based anti-icer applied with a pump sprayer before a storm — when snow falls, the bottom layer turns to slush that’s easy to shovel or sweep away.
Consider covering your deck
If you want to provide further protection for your deck, you can cover it with a tarp (making sure to secure it properly). The tarp will act as a barrier against snow and ice before a storm. However, it’s not a smart idea to let the tarp sit on your deck the entire winter as moisture can accumulate over time. Once the threat of snow, sleet, and ice is over, remove the tarp and allow your deck to remain dry.
Frequently Asked Questions
Should I remove door mats from my deck in the winter?
Yes. Mats can absorb moisture throughout winter and destroy certain parts of the deck, particularly if made of wood. This moisture could also cause mold or mildew buildup. To minimize these problems, remove mats and rugs from your deck during winter.
Does a composite deck require the same maintenance?
Since composite decks aren’t made of wood, the materials might not be as vulnerable in winter as wood decks. Still, practicing winter deck care is important to extend the lifespan of the deck. Be sure to keep the surface clear of debris, clean it properly, and promptly remove any mold or mildew. The positive news is that staining or sealing a composite deck isn’t necessary, and pests aren’t an issue.
Can I use ice melt or rock salt on my deck in the winter?
No, it’s best to avoid either product. The ingredients in ice melt and rock salt can have a terrible chemical reaction on your wood or composite decks.
Is it too late to perform deck maintenance if it’s already winter?
It could be too late to stain or apply a sealant to your deck, particularly if you live in an area that doesn’t stay above 50 °F, as cold temperatures will hamper the application. However, you can use all the other deck maintenance tips anytime in the cooler months.
