By Mark J. Donovan

January 18, 2012 4 min read

Rain, snow and ultraviolet rays can wreak havoc on a wood deck. If left unchecked, eventually deck boards will begin to fade in color, cup, check, warp and crack. Mold and mildew growth is also a common problem on frequently wet deck surfaces. Consequently, it is important to regularly weatherproof a wood deck to keep it looking beautiful and ensure its structural integrity.

To restore and weatherproof a deck to its original beauty, you first need to clean the surface. A pressure washer with a commercial deck-cleaning solution works best -- but great care needs to be taken when using the washer. Make sure to hold the nozzle approximately 18 inches away from the deck surface, and always keep it moving to ensure that you do not damage the decking boards. Also, make sure to clean the deck railings.

Power-washing a deck does not always restore it to its original color. Sometimes the boards can still look a little dark. To lighten them up, apply a commercial deck wash and brightening solution to the surface using a sprayer or long-handle stiff brush. This type of solution typically includes bleach of some percentage that will help lighten the wood and give it a more even color tone.

If you're weatherproofing the deck on a sunny day, first hose down the surface with water before applying the wash and brightening solution. After spraying on the solution, use a long-handle stiff brush to scrub the deck and remove any residual mold and mildew stains. Then allow the solution to soak into the boards for 15 to 20 minutes. Afterward, rinse off the deck with a hose.

Once the deck has been cleaned and had time to thoroughly dry, you can then begin to weatherproof it in earnest by applying a water sealer. A deck waterproof sealer is specially formulated to repel moisture and protect the wood deck boards from ultraviolet sunlight. Deck waterproof sealers are available in both clear and tinted shades. Before applying a waterproof sealer, make sure you check the weather forecast first. Typically, a deck sealer needs 24 to 48 hours of rain-free weather to dry thoroughly.

There are a number of ways you can apply a sealer to weatherproof a wood deck surface. I use a roller and a 4-inch-wide brush, as it is the most economical way to apply it. Initially, I roll the deck sealer onto a small section of the deck, and then use the brush to work the sealer into the wood.

I find this method works best, as the deck sealer really gets pushed into the wood grain. Alternatively, you can use a long-handle paint pad or buy or rent a sprayer to initially apply the sealer. As with the roller, work in small sections at a time when applying the sealer with either of these two alternative tools. Also, you'll still need to work the sealer into the wood with a brush after initially applying it.

To apply a sealer to the deck railings, a sprayer works the fastest -- but you waste a lot of sealer. The most cost-effective way to weatherproof wood deck railings is to apply the sealer with a brush. Unfortunately, it is a slow process. The water sealer will hold up best with this approach, however, and you'll save money because you'll need fewer cans of water sealer.

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