Finishes for Wood Decks

This newly revised FinishLine covers the care of wood decks, including a review of penetrating finishes including Water Repellents and Water-Repellent Preservatives, Colored Water-Repellent Preservatives, and Semitransparent Stains.

Wood decks have become an important part of residential construction, adding versatile living space to a home and, with minimal maintenance, providing decades of use. Wood decks are exposed to high levels of stress, however, from severe weather conditions that shrink and swell the wood. Without proper maintenance, wood decks can develop problems such as checks and cracks, raised grain, and mildew, thus increasing the risk of decay and insect attack.

Because of these risks, lumber used in decks is usually pressure treated with a preservative, or the lumber used is a naturally durable wood such as redwood or western redcedar. Applying an additional finish to wood decks will minimize the problems of cracking, raised grain, and mildew growth.

A penetrating finish applied to wood decks provides better overall performance and is easier to reapply than a film-forming finish (e.g., paint, solid-color stain). In addition to the continuous shrinking and swelling of the wood caused by changes in the moisture content, film-forming finishes are subjected to excessive wear, especially in high-traffic areas. For these reasons, penetrating finishes, not film-forming finishes, should be used on wood decks.