We Asked Reno Pros If You Should Waterproof Your Deck, and They All Agreed

• Waterproofing a deck can be useful for preventing water damage, wood rot, and general weakening of the deck.
• To waterproof a deck, you will need to clean it, make repairs, and let the product fully dry between coats.
• Waterproofing a deck is best done in spring or early fall when it’s not too hot or cold.

Many people have natural wood decks, opting not to stain them. But whether they’re stained or natural, do you need to worry about waterproofing?

We turned to some home reno experts to find out whether you need to waterproof your deck to extend its life.

Do You Need to Waterproof a Deck?

Whether you need to waterproof a deck or not heavily depends on the type of material that is used to make the deck.

“PVC and composite decks don’t necessarily require waterproofing,” says Chris Turner, owner and designer at Elevate by Design. “That type of material is specifically made to resist moisture, which is obviously a good thing.”

If you have a traditional wooden deck, then waterproofing is a crucial step in preserving the integrity of the structure and resisting warping, splintering, rot, mold growth, and any other damage that may be caused by exposure to rain, ice, snow, and melt water.

“What many homeowners don’t realize is that the location of the deck relative to the house plays a big role in how quickly damage occurs,” says Austin Lako, licensed residential builder and owner of Lake Effect Exteriors. “Decks that sit in shaded areas such as behind large trees, under overhangs, or on the north side of the house are more prone to moisture buildup because they dry out more slowly after rain or snow.”

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Benefits of Waterproofing a Deck

When you have a wooden deck, waterproofing is an essential step for safeguarding the wood against water damage, weakening, and wood rot.

“Waterproofing is not optional it’s what separates a deck that lasts five years from one that lasts 25,” Lako says. However, there are other benefits to waterproofing a deck that you should consider when planning your ongoing deck maintenance.

• Protects against rot and water infiltration, reducing the risk of weakening, structural failure, and decay.
• Resists mold and mildew growth, which is especially important in shaded or overly damp locations in the yard.
• Safeguards the wood against UV radiation so that the deck doesn’t fade, split, splinter, peel, or dry out as quickly as an unprotected deck.
• Improves aesthetic appeal and helps to keep the desired appearance of the deck for a longer period of time.
• Preserves the structural integrity and safety of the deck by protecting the structure from water damage that may otherwise rust fasteners, weaken support posts, deteriorate joist hangers, warp deck boards, and rot the wood.

How to Waterproof a Deck

Waterproofing the deck is a relatively straightforward job that most homeowners can handle, making it a great project for new or inexperienced DIYers to tackle.

Prepare the Area

Remove any furniture, appliances, rugs, or other items from on top and below the deck, then clean the deck with a broom or blower to get rid of loose dirt and debris.

Next, Lako suggests using “a deck cleaner designed for wood decks. Avoid harsh chemicals like chlorine bleach, which can damage wood fibers. Most manufactures of paint [or] stains have a cleaning and prep product that is sold separately. I recommend going with the manufacturers products as that should give you the best results when used in combination.”

Inspect and Repair the Deck

Check the deck for any signs of damage, like raised nails or screws, splintering wood, or cracked boards. Take the time to replace any severely damaged boards, tighten fasteners as needed, and trim vegetation to improve airflow and sunlight to the deck.

If the wood is too rough or has existing stain, paint, or sealer that is peeling, then light sanding may be required. You should also consider putting a drop cloth over any nearby plants, objects, or surfaces to protect against accidental drips, drops, or spills.

Apply Waterproofing Product

Give the deck about 48 hours to dry after washing before you begin. Once the deck is fully dry, you can begin to apply the paint, stain, or sealant of your choice. The method you use to apply the waterproofing product is largely up to your personal discretion.

“You could go with a roller or sprayer,” Turner says. “Sprayers are really convenient, but rollers are more of a surefire way to make sure you cover the entire area. Work through the deck in sections until you’ve covered the entire area.”

Let the Deck Dry and Fully Cure

After applying the waterproofing product, you will need to avoid using the deck until it has had time to dry. In most cases, the waterproofing product will take about two to four hours to dry to the touch.

At this point, you can apply a second coat, if necessary. Give the deck about 24 to 48 hours to fully dry and cure.

“The manufacture usually has a listed time for light foot traffic and a listed time for a full cure when furniture can be moved back on and the deck can be fully used again,” Lako says.

Make sure to check the manufacturer’s directions to avoid damaging the newly waterproofed surface.

When to Waterproof a Deck

Choosing the right time to waterproof the deck is important for ensuring the quality of the waterproofing project. Generally, you should check the weather report and plan the project for a few days when it’s expected to be sunny and relatively mild.

You should also consider what season is best for waterproofing the deck.

“Spring and early fall are ideal because the weather is mild, and the deck gets time to dry and cure without harsh sun or rain,” Lako says.

It’s also necessary to note that the deck will need to be waterproofed more than once during its lifespan to keep the wood in good condition.

The frequency with which you waterproof the deck tends to vary. Ideally, you should aim for “once every one to three years depending on sun exposure, foot traffic, and the type of product used,” Lako says.