Give your deck and fence a new look

Treat wood to prevent winter damage

October 29, 2004|By Stacy Downs, Knight Ridder/Tribune

The cool autumn air serves as a reminder that it's time to seal decks and fences.

The cold, snowy season is damaging to untreated exterior wood. Any time wood gets wet, it swells. When it dries, it contracts. And when it freezes, it starts splitting open and nails start to pop out.

Having a deck treated professionally can cost between $400 and $600. Prices vary depending on the deck's style, the wood's condition, the height and other factors. Fence sealing can be more expensive. The cost ranges from $500 to $1,000, depending on the intricacy and length of the fence.

To clean and seal exterior wood yourself, prepare to spend a little more than $50 for cleaning supplies, a spray applicator, sealer and bristle brush at the hardware store. If you want to get the wood especially clean, you might want to consider a power washer, which can be rented for about $60 a day at equipment rental companies, or purchased starting about $200. "People aren't always confident about using a power washer, which gets the wood cleanest," says Dave Sullivan, owner of Wood ReNew, an outdoor wood cleaning and preservation company in Kansas City, Mo. "They can gouge wood with one."

Exterior wood turns gray from dirt and the weather. When it's cleaned and sealed, the more vibrant brown color returns. People should treat their decks and fences about every 18 months to keep them looking good and to prevent mold, which rots wood, Sullivan says. Cleaning and treating wood is usually a two-day process, he says.

Stan Hendricks, assistant manager at Strasser Hardware in Kansas City, Kan., gives this advice about cleaning and sealing exterior wood: Aim for a warm day. You want it to be 50 degrees or warmer at night, and you don't want it to rain for 24 hours after you do the work.

"This is the perfect time to do it because there's not as much rain as in the spring," Hendricks says.

Day 1: Cleaning, power washing

For decks, remove everything: grills, furniture and planters. Try to remove grease stains by scrubbing them with a solution of dish soap and hot water. Spray wood with water.

Mix wood cleaner in a 5-gallon bucket. Redwood usually needs a special cleaner. Try to use a non-bleach cleaner (bleach will kill plants and grass) or use drop cloths to protect landscaping. Clean any overspray immediately with a soapy, wet rag. Spray cleanser on wood with an applicator and allow it to stay on about 20 minutes before removing it with a power washer or a garden hose.

Day 2: Sealing

Make sure wood is dry. Test by putting a few droplets of water onto the wood. If water absorbs into the wood in one to two seconds, it's ready for treatment. Set up dropcloths again. Apply water repellent sealer with a sponge mop. Treat vertical then horizontal surfaces. Use a brush to remove shoeprints or drip spots. Apply a second coat about 15 to 30 minutes later, while the first one is still wet.

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Using a power washer

- Practice. If you don't power wash correctly, you can damage wood. Practice on old boards before doing your deck or fence.

- Technique. The wand should always stay in motion when it is close to the wood. Stopping the wand while spraying will scar wood. Arc the wand up and away from the surface at the end of each stroke. Use wide strokes. Stand closer for chromated copper arsenate and other treated lumber. For softer wood, such as cedar and redwood, stand farther back. Avoid spraying windows and painted siding.

- Pressure. The most pressure you want to use on soft woods such as cedar and redwood is 1,500 pounds per square inch. Deck restoration contractors often recommend using cold-water power washers, with pressure set at 2,800 to 3,200 pounds per square inch, for CCA-treated wood. Hot-water power washers, using 2,000 to 2,800 pounds per square inch, can be used on grease and chemicals.

- Nozzle tips. Four tip sizes are usually used for power washers. The numbers refer to the degree of spray dispersal:

0: The spray pattern is a concentrated straight stream. Never use this tip for your exterior wood because it will cause damage.

15: Use for tough cleaning jobs. It's good for deck cleaning.

25: Use for modest cleaning jobs. It's good for fences.

40: Use for light cleaning jobs. It's good for more frequent cleaning jobs.

- Horsepower. A commercial-grade power washer with pressure of 2,800 to 3,200 pounds per square inch should have a 9- to 11-horsepower motor.

- Hoses. Power washers typically come with 50 to 100 feet of high-pressure hose. If you need to get the machine closer to the surface to be cleaned, it's usually best to add more supply hose (use a 5/8-inch garden hose).

- Water supply. Most power washers require 3 to 5 gallons of water per minute to operate. Know what the requirement is for your unit.

-- Stacey Downs

Sources: Do-it-yourself author James Dulley,; Dave Sullivan, Wood Re New