Protect Your Investment: Consider climate when building a new deck

If summer has taken a toll on your deck and you plan to replace it this fall or next spring, wouldn't it be nice to have a crystal ball to predict how long the deck will last, whether its color or grain will fade in the sun, or whether mildew stains will appear on shade-covered parts?

To get a glimpse into how well the almost two dozen different decking materials we recently tested might do after a year in different conditions, we left samples of each in Florida (warm, humid climate) and in Arizona (warm, arid climate); as a reference, we also kept a sample of each indoors in our labs.

(From left to right, the columns in the photographs here show the decking after one year stored in our lab; in Florida; and in Arizona. The five rows from top to bottom show the decking unwashed; washed with water and a brush; washed with OxiClean and a brush; washed with Behr wood cleaner; and cleaned with a pressure washer.)

Our testing indicates that rain and humidity foster the greatest mildew growth on composite decking materials. ChoiceDek (shown above), Monarch Exotics, Fiberon Tropics, Rhino Deck Vision Solid, and Trex Brasilia and Accents in particular showed mildew growth after a year in Florida. Symmatrix, Tamko EverGrain, and TimberTech stood out as the most resistant to mildew. Still, if you're concerned about mildew, consider using a deck stain formulated for composite decking. Also check whether the manufacturer claims its product is mildew resistant.

When it comes to wood, unless you apply a finish to preserve a wood deck—we recommend you treat a newly installed deck within a month of installation—it could turn an off color after a year or less. (Our wood decks turned gray in Florida, brown in Arizona.)

Color change in untreated decking isn't confined to wood. Trex Accents and Rhino Deck Vision Solid underwent the most dramatic color shift among composites. The plastic decking, including Deck Lok, Eon Classic, and Bear Boards, and the aluminum LockDry (shown right) we tested experienced little color change, and nearly all did an excellent job resisting mildew.—Ed Perratore

Essential information: For more details, visit our Decks & Deck Stains product page. And use our Outdoor-Living Guide to get the most out of your yard and deck, patio, or porch.