8 of the Best Deck Sealers, Tested

Hello, my friend, hello again; today we come together to talk about 8 of the Best Deck Sealers, Tested and hope the blog can help you.

We tried out today’s top deck sealers to see how well they really work. Protect your deck from damage caused by sunlight, moisture, and foot traffic with the products that excelled in our hands-on tests.

For lots of folks, the deck is a place to make memories: relaxing, socializing, just enjoying life. But the elements (sun, rain, snow, and wind), as well as people partying on the surface, take their toll, wearing away at the wood and leading to cracks, splinters, fading, and rot. We knew that using a high-quality deck sealer could reduce such damage, so we wanted to find out which of today’s deck sealers were really worth buying and relying on. Our top pick was the Seal-Once premium wood sealer, with its deep penetrating and low VOC formula.

We decided to test the most popular brands available. Our tests involved applying the sealers to decking boards, noting how easy they were to use, whether they repelled water, and how they stood up to the weather and normal wear and tear, such as foot traffic and ground-in sand.

The best deck sealer will protect the deck from damage while still allowing the natural beauty of the wood grain to show through. A clear deck sealer won’t reveal an uneven application, brushstrokes, or runs, unlike colored stain or solid paint, and sealing a deck successfully is a relatively easy task for the average DIYer. 

Read on to learn more about choosing the best deck sealer for your surface, weather conditions, and budget—and discover how the following products earned a spot in this lineup.

1. BEST OVERALL: Seal-Once Marine Premium Wood Sealer
2. BEST BANG FOR THE BUCK: Rust-Oleum Varathane Spar Urethane Deck Sealer
3. PRESSURE-TREATED WOOD PICK: Thompson’s WaterSeal Transparent Wood Sealer
4. BEST FOR WATERPROOFING: Thompson’s WaterSeal Clear Wood Sealer
5. BEST WITH UV PROTECTION: Defy Composite Deck Sealer
6. BEST LONGEVITY: ​​Olympic Maximum Oil-Based Clear Waterproofing Sealant
7. EASIEST TO USE: Eco Advance Exterior Wood Water Repellent Concentrate
8. ALSO CONSIDER: Olympic SmartGuard Clear Multi-Surface Spray Sealer

Before Buying Deck Sealer

Before choosing a deck sealer, be sure that it’s the correct product for your needs. Sealer, stain, and paint can all protect your deck from the elements, though each one has different features. According to Rafi Friedman, president of Coastal Luxury Outdoors in Jacksonville, Florida, “Deck sealer is much more important in humid conditions, and in areas with large temperature swings, especially if you get frequent freezing where you live.” He added that “if your deck is made of a fade-resistant material, I’m a fan of water-based sealers, since they last longer under all conditions.”

Paint is typically a better choice on worn decks with mismatched boards or stains that won’t come off. It covers up these issues while offering an attractive uniform finish. While a clear sealer will prolong the useful life of an older, weathered deck, it won’t update the deck’s look.

Stain, like paint, changes the color of the wood. However, instead of forming a topcoat, stain penetrates the wood fibers in the same way as sealer. Stain is beneficial for evening out splotchy color while maintaining the beauty of natural wood grain. 

Deck stain imparts a natural-looking wood color, but depending on the opacity, it can provide just a hint of color or completely obscure the wood grain, as paint would do. In addition, some deck sealers include a slight tint of color, and these stain-and-sealer combos are helpful for both protecting and refreshing the look of the wood.

If you’ve decided that stain is the right choice for you, Friedman shared more of his expert knowledge: “When you apply deck sealer, you’re sealing in anything that was in or on your deck. If you seal in moisture, your deck can continue to rot despite the sealer.” He went on to say that “this is why it’s essential to thoroughly clean and sand your deck and wait for clear, dry conditions before applying sealer.”

How We Tested the Best Deck Sealers

Testing deck sealers was relatively straightforward. We brushed (or otherwise applied) two coats of each sealer on a decking board and then tested it for water resistance and scratch resistance. However, the real measure of a deck sealer is the test of time. We would have liked to test the sealers over a few years, but we had only a month to see how well they held up to the elements. 

We positioned each test board outdoors to receive UV rays in a spot where it would be subject to the elements for a month. The temperature dipped below freezing at least 11 nights during the test phase. At the end of the month, we inspected each board for any signs of peeling and we tested again for water resistance. 

In addition to noting how well the sealers held up, we also noted how easy they were to apply and how uniformly they covered the boards. For each test, we used a rubric to record points—the better a sealer performed in any area, the more points it received. At the end of the tests, we added the points and used them to help determine the best category for each product.

Testing Stats
Products tested	8
Time spent testing	1 hour per sealer, over several days
Tests performed	9 to 10
Price range	$10 to $70

Our Top Picks

The best deck sealer should meet a user’s needs for appearance, budget, application, and drying time in addition to protecting the deck. We applied each of the following deck sealers to decking boards, noting how long it took them to dry, whether they needed a second coat, and how well they stood up to water, weather, and wear. The following deck sealers are among some of the industry leaders for maintaining wood decks, well-suited to various deck specifics. Learn the pros and cons of each product, and find out how they earned a spot on this lineup.

Best Overall

Seal-Once Marine Premium Wood Sealer

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Our Ratings: Application 4/5; Appearance 5/5; Durability 5/5; Value 5/5

Product Specs 

• Type: Water-based 
• Weather resistance: UV and moisture resistant 
• Coats required: 2

Pros

• Deeply penetrating formula; does not allow any water to penetrate after dry 
• Applies clear; does not alter the color or finish of the wood
• Low VOCs; ideal for those that prefer eco-friendly or low-chemical products 
• Resists salt, mold, and algae; perfect for those that live in the outdoors or near water 

Cons

• Some users have reported thin application texture; may require many coats  

When we opened the can of Seal-Once Marine Premium Wood Sealer, the first thing we noticed was that something was missing. The smell! Sealers are notorious for emitting toxic odors, but this low-VOC sealer had virtually no smell at all.

We started testing by applying a thin layer of sealer to a decking board with a brush. Though it looked slightly milky, it became clear as it began to dry. In 45 minutes, when the surface was still somewhat damp (as recommended), we applied a second coat. After that, we set the board aside and let it dry 24 hours before continuing our tests.

When completely dry, we tested for water resistance by spraying the board with a hose. On the untreated section of the board, the water soaked in. On the section treated with Seal-Once, the water beaded up and ran off.

We then placed the board flat on the ground and sprinkled sand on it, after which we walked over it numerous times to mimic foot traffic on a real deck. After sweeping the sand off, we inspected the surface for scratches. We found minor scratches on both the treated and untreated sections of the board, but the scratches were shallower on the sealed area.

Finally, we left the board outdoors for a month of harsh sun rays, wind, rain, and even freezing nighttime temps. After which, we scrubbed the board clean with a nylon-bristle brush and an all-purpose household cleaner and let it dry. We then tested once more for water resistance, and the water again beaded up on the sealed section of the board. While we don’t know how this sealer would survive a harsh winter or a couple of summers, it held up well in our 1-month testing window.

Get Seal-Once deck sealer at Amazon or The Home Depot, or Walmart.

Best Bang for the Buck

Rust-Oleum Varathane Spar Urethane Deck Sealer

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Our Ratings: Application 3.5/5; Appearance 5/5; Durability 5/5; Value 5/5

Product Specs 

• Type: Oil-based 
• Weather resistance: Water and UV resistant
• Coats required: 2 to 3

Pros

• Semigloss finish provides a sleek look to outdated wood or decking 
• Protects against mold and mildew; ideal for those that live in moist environments 
• Scratch resistant finish keeps the deck looking fresh in the long-term 
• Lasts for up to 5 years; little to no maintenance required after first applied 

Cons

• Requires a minimum of 3 coats to keep wood surfaces protected 
• Strong fumes may be emitted during the application process 

Protecting the backyard deck doesn’t have to cost a fortune. Rust-Oleum’s Varathane Ultimate sealer adds a layer of defense against the elements while giving a deck an attractive semigloss sheen. (Spar is a term traditionally used to designate high-quality varnish used on boats.) 

We brushed on a light coat of this spar urethane, and it went on smoothly and uniformly. It has strong fumes, so we opened a window and turned on a fan while working with the product. This sealer takes slightly longer to dry than some of the others we tested, and the manufacturer suggests a minimum of three coats, so we applied the subsequent coats 4 hours apart. We then waited a recommended 3 days after the final application before starting our tests.

When we sprayed the board with a hose, the water on the sealed section of the board beaded up and ran off. We sprinkled sand over the surface and walked back and forth on the board; after brushing the sand off, we saw scratches on the non-sealed section but none on the area we’d sealed with the spar urethane.

After a month in the sun, wind, and rain, we scrubbed the board with a brush and all-purpose cleaner, let it dry, and retested it for water resistance. The water beaded up once again. The unsealed section of the board had weathered some, but the part sealed with Varathane’s spar sealer was still bright and new looking.

Get Rust-Oleum Varathane deck sealer at Amazon, Ace Hardware, The Home Depot, or Walmart.

Pressure-Treated Wood Pick

Thompson’s WaterSeal Transparent Wood Sealer

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Our Ratings: Application 4/5; Appearance 5/5; Durability 5/5; Value 4.5/5

Product Specs 

• Type: Water-based 
• Weather resistance: Moisture and UV-protected
• Coats required: 1 (2 for deeper color)

Pros

• Adds a small amount of color to wood for those that want a deck refresh 
• Fade-resistant formula keeps wood and decking looking fresh for years 
• Requires just 1 coat for full protection; requires a lot less work than comparable options 

Cons

• Thin consistency may lead to messy application

Treated wood—such as white pine or fir that’s been saturated with chemicals designed to limit weathering—can take on an unappealing greenish tint. Applying a sealer that has a bit of color can counteract the greenish hue while protecting the deck.

We tested Thompson’s WaterSeal Transparent Waterproofing Stain in maple brown, and it imparted a hint of color—not enough to change the look of the wood grain but just enough to enhance it. (Since we tested this product, Thompson’s has updated the look of the bottle and the name of the product and stain, though the formula is the same. It’s now known as Thompson’s WaterSeal Transparent Wood Sealer in Desert Tan.) The sealer is thin and watery, so it’s kind of messy to apply with a brush. It would probably be more suitable for an airless spray rig, but we didn’t have one available. This product had some fumes, but we found it tolerable.

The sealer started to soak in right away, and the manufacturer recommends just one or two coats, the second coat if a deeper color is desired. We gave the board two coats and then let it dry for 24 hours before continuing our tests. When sprayed with the hose, water beaded up on the sealed section of the board but soaked into the bare, untreated section. Although the color was slightly different where we applied Thompson’s WaterSeal, no other difference was visible—no surface sheen was apparent, and the wood grain was still prominent.

After sprinkling on the sand and walking on it, we did notice scratches on the sealed section, but the scratches did not reveal fresh (unstained) wood beneath. This suggested to us that the sealer had penetrated deeper than just the surface of the wood.

Once a month in the sun and elements had gone by, we gave the board a good scrubbing. Thompson’s WaterSeal Transparent sealer continued to protect the wood from moisture, as the water beaded up and ran off.

Get Thompson’s transparent deck sealer at Ace Hardware or Lowe’s.

Best for Waterproofing

Thompson’s WaterSeal Clear Wood Sealer

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Our Ratings: Application 3.5/5; Appearance 5/5; Durability 5/5; Value 4.5/5

Product Specs 

• Type: Water-based 
• Weather resistance: UV and moisture resistant
• Coats required: 1 to 2

Pros

• Applies clear; does not alter the current look or finish of the wood or decking 
• Protects against mold and mildew; suitable for those that live near water or in moist environments 
• Scratch-resistant finish keeps the deck looking fresh for years 

Cons

• Thin and runny formula may be messy to apply 
• Slight odor but tolerable; some users may want to wear a mask while applying 

Thompson’s WaterSeal Clear Wood Sealer’s penetrating protection will provide a robust defense against the elements without changing the wood’s natural color or adding a sheen. This makes it well suited to exterior woods with desirable coloring such as cedar and redwood. 

As the second Thompson’s WaterSeal product we tested, this sealer was also thin and runny. However, unlike the Thompson’s stain/sealer combo, this formula created a clear but visible layer on the surface of the decking board. We applied a second coat (although the manufacturer claims that one is often sufficient) and then waited the recommended 48 hours for the sealer to cure before continuing the tests.

This clear Thompson’s WaterSeal repelled water as well as the transparent product, and it seemed to withstand scratches even better. We couldn’t find any scratches on the sealed section of this test board, so we set it out to weather the elements for a month. Once the month was up and the board was scrubbed and dried, the clear sealer repelled water just as well as before, and the wood beneath the sealed section still looked fresh and new while the untreated area had weathered some.

This sealer also purports to protect wood from mold and mildew, making it optimal for rainy areas, but we were unable to test that feature. However, this product provided a protective layer and preserved the color of the wood, so we feel it would be a beneficial treatment to keep wood decks looking good.

Get Thompson’s clear deck sealer at Amazon, Ace Hardware, Lowe’s, Blain’s Farm & Fleet, or Walmart.

Best with UV Protection

Defy Composite Deck Sealer