What Kind of Wood for a Deck to Seal?

Pressure-Treated Pine

• Pressure-treated pine is one of the most common types of wood used in making decks. It is relatively inexpensive, but stands up well to sunlight and rain. As with any type of wood used for a deck, pressure-treated pine should always be sealed once the deck has been built. Staining is optional, though treating the wood with an oil-based polyurethane will give it a warm amber glow once the polyurethane dries.

Cedar

• Cedar is another common option for decks and wood siding and shingles. Cedar can be painted, stained or left alone before being sealed. Once the original finish starts to fade or peel, cedar decking can be renewed by power washing before being refinished with fresh paint or stain. As with pressure-treated pine, cedar can be treated with oil-based polyurethane to achieve a warm amber finish. Water-based polyurethane may also be used if you prefer to preserve the wood grain. When selecting cedar for your deck, pick wood that has been cut from heartwood; you can get this information from the staff at a lumberyard or home improvement center.

Redwood

• Unlike pine and cedar, which tend to be on the tan and yellow spectrum, redwood is typically light red to a dark reddish brown, depending on the species. While aesthetic appeal is important, it is more vital that you choose a redwood grade that stands up to decay. When selecting redwood for your deck, pick anything with a grade of "Clear Heart" or "Heartwood Common." These grades of redwood are the most resistant to decay, which makes it better suited for outdoor building. Using oil-based polyurethane will add a light amber hue to the wood, but the natural red tends to overpower it.

Mahogany

• Although less common than pressure-treated pine, cedar and redwood, mahogany is a fairly popular choice for decking because of its woven-pattern grain. Mahogany is typically not graded in the same way that redwood is, but you can determine whether a species of mahogany is appropriate for a deck by inspecting the grain. Medium- to dark-red or brown grains are generally more resistant to lighter-grain mahogany. As with redwood, oil-based polyurethane can give the mahogany an amber hue, but this will likely be overpowered by the grain. Most mahogany is imported, making it the more expensive choice for building a deck.