See text for key to these materials.
Lumber is divided into grades based on the number of obvious flaws, such as knots, sap pockets, splits, and other blemishes. Use the straightest, best-looking boards for deck surfaces that will show, but save a little money by buying mid-grade lumber for the unseen underpinnings of the deck's structure. Stay away from the lowest grades, however. Knotty or warped lumber will be difficult to work with and can weaken your deck.
When it comes to durable decking materials, there are three basic choices: wood that has been treated to resist rot, wood that is naturally rot resistant, and synthetic materials.
- Pressure-treated lumber (C & D). The least expensive and most popular deck material in use today is pressure-treated lumber. It's usually made of pine or fir that is treated with preservatives to resist moisture. Look for lumber labeled either "kiln-dried" or "kiln-dried after treatment," and choose from either green (D) or brown (C) to suit your aesthetic preference. You should allow pressure-treated lumber to weather for at least 90 days before you stain or paint it. Arsenic-free preserved lumber is treated with a preservative that is easier on the environment, and comes out darker so it doesn't need to be stained.
- Rot-resistant wood (A & B). Species such as cedar (B), cypress, and redwood (A) naturally resist rot and decay, and they are easier to saw and nail than pressure-treated lumber. While these species are structurally strong, their surfaces are soft, making them prone to denting and marring. They may require careful handling during construction. Costs for these species vary depending on the region in which they're sold, but across the board, they're more expensive than pressure-treated lumber. You may want to try reducing your costs by using more expensive wood species for visible components, such as railings, built-in benches, and decking, while substituting less-expensive, pressure-treated lumber for the structural framing.
- Synthetic materials. If low maintenance is your key concern, consider synthetic materials. Plastic lumber, which is made of recycled milk jugs and grocery bags, does not absorb moisture. Molded in various colors, plastic lumber can be painted, but it will never quite take on the look of wood. For proper installation, you need to use sliding clips because plastic expands and contracts in temperature extremes.
Vinyl lumber comes in white and several additional colors. Its pros and cons are similar to plastic lumber. Purchase brands that have the UV inhibitors impregnated directly into the vinyl and not sprayed on after production.
Wood-polymer lumbers are another option. They contain up to a 50 - 50 ratio of waste wood and recycled plastics and can be stained or painted. These products look and feel like wood but never require maintenance.
Rubber lumber is relatively new to the market. This material is composed of 50 percent plastic and 50 percent old tires, helping to solve the problem of what to do with worn-out treads. The material, used originally for commercial applications such as flooring in livestock trailers, is tough, durable, and impervious to water, insects, and UV rays. It comes in three colors, but the color isn't warranted to last.