The Best Deck Sealers for Protection Against the Elements
Protect your wooden deck from damage caused by moisture, sunlight, and mold with the right deck sealer for your needs and budget. Ahead, get our top tips and recommendations.
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- Best OverallSeal-Once Marine Premium Wood SealerCheck Latest Price
- Easiest ApplicationEco Advance Exterior Wood WaterprooferCheck Latest Price
- Best ValueOlympic Smartguard Concentrated SealantCheck Latest Price
The deck functions almost as the living room of outdoor space. It’s a great spot to barbecue a batch of burgers with the family or spend a quiet evening relaxing with a glass of wine.
But as with all things made of wood, decks are subject to deterioration from exposure to the elements. Sun, rain, snow, and wind all take their toll, wearing away at the wood and leading to cracks, splinters, fading, and rot. That’s why it’s so important to protect your deck with regular applications of deck sealer.
The best deck sealers protect wood decking from damage, while still allowing the beauty of the wood’s natural grain and color to show through. That’s why sealer—as opposed to deck stain—is the preferred finish for many decks.
Read on for our guide to navigating the available options—and don’t miss our top picks, below!
- BEST OVERALL: SEAL-ONCE MARINE Penetrating Wood Sealer
- EASIEST APPLICATION: Eco Advance Exterior Wood Water Repellent
- BEST VALUE: Olympic Stain Smartguard Concentrated Sealant
- LONGEST-LASTING SEAL: Olympic Stain Maximum Waterproofing Sealant
Before You Buy
First be certain that deck sealer is the correct product for your needs. Many people aren’t clear on the differences between sealer, stain, and paint. They all can protect your deck from the elements, but their features differ.
Sealer sits on the surface of the wood, offering a clear coat of protection that lets the wood grain show through. Decks constructed from naturally beautiful woods such as cedar, redwood, mahogany, or exotic ipe should retain their character. But do note that wood sealers mostly prevent damage from moisture; they don’t block out damaging UV rays that break down wood fibers and fade color. That means that over time, your sealed wooden deck will tend to weather to a silvery gray, regardless of its original color. On the plus side, sealing a deck is an easier task for the average DIYer than staining it, since clear sealant won’t so easily reveal uneven application, brush strokes, or drops the way colored stain will.
Stain penetrates into the wood fibers and changes the color and add protection against UV damage. Stain is the best choice when you want the beauty of a natural wood color on a deck made with less attractive wood, such as pressure-treated pine or fir, or one heavily stained or excessively weathered. Unlike clear sealers, these finishes come in a huge range of color hues, including just about every tone of wood, so you can bring back your deck’s original appearance or change it to something new. Stain also generally lasts longer. You’ll typically need to reseal your deck every year, but a stained deck might go two or three years between touch-ups, depending on the severity of the weather in your area.
Paint is an opaque surface coating that conceals the wood’s natural appearance completely. That makes paint the better choice when you want to completely cover up unattractive or damaged wood, or you want a deck in a color other than a natural wood tone.
Oil-Based or Water-Based
You’ll find both water-based and oil-based deck sealers, although most people choose water-based products. Still, both have their pros and their cons.
- Ease of application: Oil-based sealers can be trickier to apply. If the deck isn’t absolutely dry when you apply an oil-based sealer, it’s likely to develop small bubbles or spots as the moisture tries to evaporate. Water-based sealers, however, won’t be affected if you apply them over slightly damp, but not wet, wood.
- Environmental concerns: Water-based sealers give off less volatile organic compounds (VOCs) and aren’t as hard on your lungs or the environment. This can be the major deciding factor if you live in a city with strict regulations regarding VOCs.
- Cleanup: Oil-based sealers require paint thinner or a similar solvent to clean off your brushes and tools after application, whereas water-based sealers clean up easily with just water and soap.
- Dry time: Depending on the weather, an oil-based sealer might take as long as two days to dry completely. Water-based sealers typically dry much faster, often in as little as three hours.
- Durability: Over time, particularly if the weather is extreme, water-based sealers can flake or chip, which is rarely a problem with an oil-based product.
- Preparation: When it’s time to reseal your deck, you’ll often find that oil-based sealers are more forgiving than their water-based counterparts. You’ll need to clean and prep the deck before applying either type of sealer, but oil-based products are generally a little easier to smooth on evenly over slightly rough wood or imperfections.
- Cost: Oil-based sealers usually are less expensive than water-based products, which often cost twice as much per gallon.
Water and Mildew Resistance
Sealers help protect wood from the damaging effects of moisture. By drying into a solid protective coat of polymer, the sealer can prevent rain, snow, humidity, and sprinkler runoff from soaking into the wood fibers. If wood remains unsealed, however, moisture eventually leads to swelling, splitting, and rot. Some products even include mildewcides, which are chemicals that kill fungal spores. In damp climates, the growth of mold or mildew on wooden decks can be frustrating because the white or black splotches are unsightly and difficult to eliminate. If you live in a rainy or high-humidity climate, look for a sealer that fights fungus as well as water.
The sun’s UV rays are merciless: Beating down day after day, they can damage the cell walls of all living things, including wood. That damage shows up on your deck in the form of fading, cracking, and warping. Wood stains offer a great deal of UV protection thanks to added color pigments—the darker the stain, the more UV protection it provides. Clear deck sealers block out little or no damaging UV light. That’s why it’s important to look for a product with additional UV protection if you live in an area with intense summers. Note, however, that even a sealer with UV protection will merely slow the rate of sun damage to your deck, not entirely prevent it. Because the chemicals used to block UV rays tend to break down fairly quickly, even within a few months in an especially hot and sunny climate, you need to be vigilant about reapplying the sealer each year before summer sets in.
Most deck sealers require two coats for the best performance, but a few products can get the job done with just a single coat. That’s a big time-saver, although of course you’ll pay more for a single-coat sealer.
Our Top Picks
1. BEST OVERALL: SEAL-ONCE MARINE Penetrating Wood Sealer
SEAL-ONCE MARINE Penetrating Wood Sealer is a clear water-based sealer, but it provides the protection you’d expect from an oil-based stain, penetrating right down into the wood fibers for long-lasting protection against moisture damage and mold growth. Because the sealer penetrates into the wood, rather than merely forming a coating, it expands and contracts as the wood fibers respond to temperature changes. This means no fear of cracking or peeling, even in the hottest summers or coldest winters. Plus, the sealer is ultralow in VOCs, so it won’t harm people, pets, plants, or marine life. It also cleans up easily with soap and water and helps your deck resist damage from water, salt spray, mold, and algae.
2. EASIEST APPLICATION: Eco Advance Exterior Wood Water Repellent
Eco Advance Exterior Wood Water Repellent goes on easily. Just mix the concentrate with a gallon of water, pour it into your garden sprayer or deck sprayer, and cover your deck with a light coat of the formula. It goes on a milky white, making it easy to see where you’ve sprayed, but dries crystal clear in less than two hours. Even better, it won’t harm your lawn or outdoor plants. It’s low in VOCs, has little odor, and is nontoxic to you and your pets. Eco Advance Exterior Wood Water Repellent delivers protection against moisture, mold, pool chemicals, de-icers and oil.
3. BEST VALUE: Olympic Stain Smartguard Concentrated Sealant
Olympic Stain Smartguard Concentrated Sealant is a well-priced sealer that comes in concentrate form. Just add two gallons of water, pour it into your garden or deck sprayer, and give your wooden deck a couple of coats. It dries in just one hour—even on wood that’s damp from rain or cleaning—so you’ll be enjoying your deck the very same day you seal it. The sealer prevents water damage, helping prevent rotting, splitting, and warping.
4. LONGEST-LASTING SEAL: Olympic Stain Maximum Waterproofing Sealant
Typically, sealing a wooden deck is a once-a-year chore, but Olympic Stain Maximum Waterproofing Sealant lasts up to three years. The sealer protects against rotting, cupping, and staining caused by water and humidity, and it also includes UV protection to ward off fading and warping from sun exposure.