Wood Decks, Restoring & Maintaining Wood Decks

For some contractors, the prospect of restoring a weathered wooden deck has about as much appeal as getting a big splinter in their finger.

“A lot of painters don’t want anything to do with decks,” says Jake Clark, president of Armstrong-Clark Co., a wood-care product maker in Long Barn, California. “Homeowners see decks in Sunset Magazine every month, and they’re beautiful and pretty, then they look at their own deck, which was just done last year, and it looks like hell.”

That isn’t, of course, necessarily the fault of the painter who worked on the deck. Stepped on, rained on and baked by the full strength of the sun like they are, decks simply need more frequent attention than other coated surfaces around the house. But while some contractors see this as a curse, others recognize it as profitable niche.

“I have a lot of repeat customers whose decks I restored once and now do a light cleaning on every year,” says Dan Butler, a painter and the owner of Pressure Clean Power Washing Co. in Manchester, N. H. Decks constitute about 60 percent of the work he does, though he could easily do more, he says. “I could probably find enough work to keep me busy for the rest of my life. But it’s not easy work, by any stretch,” he says.

Cleaning an older deck
The toughest restoration jobs involve stripping multiple layers of old coatings down to bare substrate. Sometimes, though, all a tired deck needs is a good washing. A stiff-bristled brush and mild detergent might work in the very easiest cases. For tougher jobs there’s a variety of commercial cleaners formulated to rid decks of mildew, algae, dirt and stains.

Pressure washing is also an option, though a potentially risky one. A bungled pressure-washing job can gouge the wood, raising the grain and fuzzing the surface. With care, though, a pressure washer can quickly and safely strip away many evils. If mildew is one of them, bear in mind that a pressure washer will blast away the surface stain without touching the live spores lurking in the grain.

For wiping out mildew entirely, chlorine bleach is a popular and inexpensive option. Some commercial deck-cleaning products use chlorine bleach as a key ingredient. Many contractors swear by homemade solutions of household bleach, not only for mildew-busting but for general cleaning and wood brightening.

But chlorine bleach has some significant drawbacks, notwithstanding its popularity. Unless it’s combined with a detergent, it will merely lighten dirt and residues without removing them, creating an illusion of clean. “Bleach kills the mildew but leaves the dead body,” says Vinod Jhamb, vice president of marketing for Napier Environmental Technologies Inc., which makes a line of environmentally friendly deck restoration products.

Chlorine bleach is also notoriously hard on the environment, not to mention the people who use it and the wooden decks they use it on. “Over time it will actually degrade the lignin in the wood, damaging the wood’s cellular structure and making an unsound surface to put a coating on,” says Leslie Juhn, category manager for Wolman Wood Care Products, in Somerset, New Jersey. Deck cleaning products containing oxygen-based bleaches are preferable, she says.

Oxygen-based bleaches have a gentler impact on vegetation, painters and decks, even as they rain death upon mildew spores and obliterate stains caused by leaves, flower pots, dripping eaves and other sources. Oxygen-based cleaners (which utilize the same active ingredient found in some laundry detergents, sodium percarbonate) come in powdered concentrates which fizz when mixed with water as hydrogen peroxide and soda ash form. “A good deck cleaner will actually loosen and lift off that top layer of weathered, gray wood cells,” says Juhn. “Sodium percarbonate has a foaming action that lifts and loosens that top layer. It’s strong enough to attack mildew, yet it rinses off into the grass, plants and shrubs without harming them.”

For redwood decks and cedar decks, cleaners containing oxalic acid are the norm. Oxalic acid strips away those dark tea-colored stains caused by tannin bleed, a common occurrence on uncoated redwood and cedar. Oxalic acid also eliminates nail bleed and other rust stains on all types of wood, and it wipes out mildew as well. It’s the key ingredient in many wood revivers and brighteners.

Jack Scialabba, owner of Jax Painting Co. in Twain Heart, Calif., prefers oxalic acid to bleaches. “I always try to think of maintenance down the road and what’s safest for the deck, and oxalic acid is the better way to go,” says Scialabba, who does a fair share of annual deck-maintenance visits.

Citric acid, which is gentler than oxalic acid, has been growing in popularity in deck cleaning products. It works especially well for cleaning hardwoods. Trisodium phosphate is another commonly-used cleaning agent. It works well for cutting through grease.