Choosing The Finish
Ask yourself how you want your deck to look. Do you want to paint it, stain it, or let it weather? With a clear finish, redwood and cedar show off their natural color. They also look good when left to weather. On the one hand, some designs seem made for paint. Others, especially those in woodland settings, might look better weathered. What about your design?
- First consider the style of the deck and its setting, including colors on your home.
- Then turn your attention to what color, tone, and surface sheen (flat or glossy) complements the overall landscape design theme.
- Finally, research the durability and ease of application of various products.
If you mix finishes, make sure they’re compatible. Your supplier will be able to help you choose the right combination.
SEALERS: Sealers, also called water repellents, seal wood against water penetration. You have two basic options— clear or pigmented sealer. Both protect the wood but don’t change its appearance appreciably.
A wide range of additives increases the effectiveness of sealers.
- Fungicides and insect repellents ward off mildew, insects, and fungi.
- Ultraviolet blockers diminish the effect of the sun’s rays and help maintain the natural color of the wood.
All-purpose sealers usually contain water repellents, preservative, and ultraviolet blockers. A clear sealer has the least effect on the wood’s natural color. It may slow the graying of wood but won’t stop it. Pigmented sealers provide the same protection but change the color of the wood slightly. You can apply sealers over or under stains and under primer and paint for extra protection.
STAINS: Stains change the look of a surface, but most are not designed to protect the wood. Stains are somewhat less expensive than paints, and application goes faster than painting because stains don’t require an undercoat. They go on easily over rough or smooth surfaces.
Stains fall into two general categories based on the concentration of pigment:
- semitransparent stains allow the wood grain to show, but they wear away more quickly. They are particularly suitable for highlighting the beauty of wood grain.
- heavy-bodied stains contain more pigment and tend to obscure the grain more.
No matter what their pigment level, stains don’t offer much variation in sheen. They tend to retain the wood’s low-luster, natural look.
Both kinds of stain come as oil-based or water-based products. In general, oil-based stains are more durable than their water-based counterparts. But new chemical techniques are producing water-based products that rival oil-based stains. Ask your retailer for recommendations. On redwood and red cedar, however, apply oil-based stains.
Even if you’ve decided on a heavy-bodied stain for the frame of your deck, consider a semitransparent product for the decking. The inevitable wear won’t be as noticeable on a light color, and the slight difference in tone can often produce a pleasing contrast with the rest of the deck. Periodic restaining will give you a more even color. In any case, make sure you apply a nonchalking stain or sealer-stain to eliminate the possibility of tracking a powdery film into the house.PAINTS: Painting a deck creates an elegant, refined look. Unlike stain, its opaque film can mask some of the defects in the wood, making it an ideal finish for lower grades of lumber.
Paint offers an unlimited choice of colors and looks the same on all species. Paint takes more time to apply, however, is more expensive, and is harder to maintain than other finishes. All of this inconvenience is balanced by the fact that it offers the most complete protection. But once you have painted a deck, you can’t change your mind and apply any other finish.
If you’re painting, apply primer first. Painted finishes tend to last longer and look better on smooth surfaces than on rough ones. And, of course, they can be recoated.
Here again, you have choices:
- exterior alkyds (oil-based products) are costly, require solvents for cleanup, and dry slowly.
The weathered look
If you want your deck to have a gray, weathered look, the easiest “finish” is to do nothing. Just let the wood weather naturally. This process works best with all-heartwood grades of a durable species, such as cedar, cypress, or redwood.
The final color and length of the aging process varies with the species and its exposure, but generally cedar and cypress weather to a light, silver gray; redwood turns dark gray; and pressure-treated lumber turns a soft gray, while retaining a hint of its original green or tan coloring.
These treatments change the appearance of wood by lightening its natural tones.
Bleaching treatments offer an intermediate solution to the problem of toning down the jarring look of a brand-new deck. They soften the raw-wood look and help the varying shades of natural wood to blend in. You get the effect of two seasons of natural weathering in one application because, like the sun, the treatments strip color from the wood fibers. These treatments don’t protect the wood, and some products are harmful to plants and grasses.
Sealers stop the bleach from working. So if you plan to bleach the wood, don’t seal it first. Wait two months after applying the bleach to seal the wood.
Finishes and pressure treatments
Most pressure-treated wood is kiln-dried before preservative is applied. This means that a great many boards are still soaked when they get to the lumberyard—and when you bring them home. Wet wood won’t take a finish and will cause it to blister and peel. Some boards may be dry to the touch but still contain enough moist chemicals to resist finishing. You can build your deck with freshly treated lumber, but you’ll have to let it dry—sometimes several weeks— before applying a finish. Try the “bead” test.
Sample a section
Before applying any finish, test the final color by applying a small sample in an out-of-the-way spot on your deck. Let the finish dry to make sure it produces the color you want. In general, paints dry darker than when wet. Stains dry lighter.
- Water-based latex paints don’t cost as much as alkyds, clean up easily with water, and dry quickly.
Both kinds come in a range of sheens: gloss, semigloss, flat, or matte.
- Oil-based primers provide better protection on raw wood than water-based primers. You can add stain blockers to stop bleed-through from redwood and cedar. A good-quality acrylic-latex top coat applied over an alkyd primer is probably the most durable and protective finish.
When painting the decking itself, choose a product specified for outdoor decks or porches so it will withstand heavy wear. Like painted porches and steps, a painted deck surface can be slippery when wet. As an extra safety precaution, especially around doorways and stairs, you can mix a handful or so of clean sand (play sand for sandboxes) with the paint used for the final coat.
It’s best to apply finishes to the wood before assembling the deck. That way you’re assured of preserving all of the surfaces. It’s also easier to apply finish when the deck is in pieces, as you won’t have to crawl underneath the deck, for instance, to finish the bottom of the decking. For most do-it-yourself decks, this step will prove impractical, especially if you’re curring materials as you assemble the deck. But at a minimum, coat at least the exposed end grains that will be hidden in joints. It’s th end grain that tends to wick up water and rot first, so give these board-ends a good soaking. Some deck builders prefer to dip end grain in a shallow pan of preservative rather than to apply the preservative with an applicator.
Whether the components are assembled or unassembled, however, it’s important that the wood is dry. Pressure-treated wood might require several weeks before the moist preservative cures out of the wood. Even with naturally resistant species, it’s wise to wait a week or so before applying the finish.
If you’re applying a sealer, use a good-quality roller that has a 1-inch nap. That way you’ll get good coverage and better penetration than with other applicators. You can recoat most clear sealers while they are still wet.
The Bead test
For all other finishes, you can use a brush, pad, roller, or sprayer. Larger projects will go more quickly with a sprayer. Rent an airless model—they produce less overspray—but practice on scrap wood first.
If you’re recoating an existing surface, give it a good cleaning. Scrub it with a moderately stiff brush and a solution of cup household chlorine bleach and gallon water, then rinse it well. If the deck has weathered naturall for some time and you would like to restore the original wood color, use a bleaching agent, and be sure to protect any nearby plantings. As an alternative, you can use a pressure washer to remove surface dirt and restore the wood’s natural color prior to restaining or resealing.