CHOOSING A DECK FINISH

Awooden deck that’s coated with a finish will likely need to be refinished every three to five years. With an entire aisle devoted to finishing products at the home center, how do you decide what’s best?

The steps involved with using oilbased vs. water-based finishes, and the maintenance required, will help drive your decision. Manufacturers’ claims about how long a finish lasts should be taken with a grain of salt; the life span of any finish on wood that’s exposed to the elements is unpredictable.

As you choose a deck finish, keep these facts in mind:

Oil-based

Easy to apply because of the slower drying time. Penetrates the wood and doesn’t form a film. Takes longer to dry. The wide temperature parameters for application let you apply it earlier or later in the season than water-based finishes. Doesn’t crack or peel. You can refinish just a small area. Regular cleaning is recommended.

Water-based

Dries fast, making application more difficult than oil because it’s harder to keep a wet edge. Forms a protective film. Will likely crack and peel. Must be completely removed before refinishing.

No finish

Use pressure-treated lumber or a rot-resistant species such as cedar or redwood. No refinishing or the accompanying prep work required. Requires periodic cleaning as needed. Boards will weather to a silver/ gray patina. With good airflow, the deck will last for decades.

Prep work is everything

When it’s time to refinish, the first step is cleaning. Pressure washing can loosen the wood fibers and hasten the breakdown of the wood, so don’t do it unless you’re experienced with the proper pressure and angles for cleaning wood. Deck cleaners and scrub brushes are a much safer option.

The remaining prep work depends on the type of finish that’s currently on the deck. You can apply an oil finish over an old oil finish with minimal prep and expect good results. But if the old finish is water-based and you haven’t thoroughly removed it before applying an oil-based finish, the penetration of the oil-based finish will be blotchy. If you don’t know whether the old finish is water- or oil-based, here’s how to tell:

If the old finish absorbs water and isn’t peeling or cracking, it’s most likely oil-based. In this case, use a deck cleaner with a scrub brush to clean the surface. Apply your new finish according to the directions on the can.

If the old finish is cracking or peeling and/or doesn’t absorb water, it’s likely water-based. To remove water-based finishes, you’ll need to use paint stripper as well as a fair degree of sanding before applying your new finish.

For a new deck that’s never been finished, wait a year before applying any finish. During the waiting period, clean with a deck cleaner and a scrub brush at three to six months, and then again right before finishing.