Advice on Waterproofing Your Deck

Tips on How to Seal a Deck for Keeping it Looking like New

By Mark J. Donovan

Once you’ve constructed your new deck, the work unfortunately doesn’t end there. Particularly if the deck was constructed out of wood decking material you’ll need to waterproof your deck periodically, usually every couple of years. Waterproofing your deck is critical for protecting it against nature’s elements and to ensure it keeps looking beautiful for years to come. Sealing a deck prevents water from penetrating into the wood. If water is allowed to absorb into the wood, rot, and mold and mildew growth is inevitable. It also protects the deck from the harmful ultraviolet rays of the sun which can bleach out the color of the deck and contribute to dry rot.

Also, after spending a small fortunate on building your deck you’ll undoubtedly want to protect your investment and ensure that it continues to complement the exterior of your home, rather than detract from it. Waterproofing the deck also helps to preserve the original color and beauty of the deck.

Depending upon the type of decking material used you may need to wait a couple of months for the decking boards to dry out prior to sealing the deck. This is particularly true if using green pressure treated decking lumber. With other types of wood decking products, such as redwood, it’s preferable to seal this type of wood decking prior to actually installing it. Again, expect to have to apply a fresh coat of deck sealant very 18 to 30 months, depending upon your local climate conditions.  Tips on waterproofing your mahogany deck.

When waterproofing a deck make sure that the weather forecast calls for clear skies and no rain for at least 24 hours, and preferably 48 hours, after applying the deck sealer. Otherwise you may end up with a permanently tacky deck. Also, make sure the deck has been thoroughly swept and cleaned prior to waterproofing the deck. Preferably use a deck cleaning agent with a mildewcide in it to remove any mold and mildew growth on the deck surface.

If you choose to use a power washer to clean the deck, be careful not to damage the wood decking surface by positioning the spray nozzle too close to the deck surface. Doing so can cause the wood grain to become damaged, which will result in a non-uniformed look on the sealed deck

The deck surface should also be thoroughly dry prior to applying the deck sealer. In addition, prior to applying the deck sealer, you may want to first apply a deck cleaning solution to restore much of the original color to the deck. Again, it is critical that the deck has had time to thoroughly dry prior to waterproofing it.

When applying the deck waterproofing solution, make sure not to apply it too thickly, or otherwise you may end up with a permanently tacky deck surface. Peeling will also result in short order.

Deck Installation Bid Sheet

I typically like to roll the deck sealant on with a thin napped roller and then go back behind it with a 4 inch wide brush to work the sealant into the wood.

After waterproofing the deck, wait 24 hours prior to walking and placing deck furniture on it.

For help on building a deck, see’s Deck Installation Bid Sheet. The Deck Installation Bid Sheet will teach your how to hire the right deck contractor, and help to ensure that your deck project is completed on time and budget.

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