🚧 Environmentally advanced wood preservatives | Treated Wood

Care & Maintenance

Cleaning a wood deck

Cleaning Wood Decks

A wood deck requires regular maintenance just like any other major part of a home. Regular cleaning and application of a high-quality stain and sealer will help protect your deck from the weather and ultraviolet ray damage caused by the sun and will extend the usable life of the deck.

Wood deck cleaners come in various ingredients and concentrations for varied applications—spray, scrub and power wash. The purpose of wood deck cleaners is to remove dirt, mold, algae and oxidation (graying).

Because most deck cleaners raise the pH in wood, deck brighteners are important to neutralize cleaners to leave the wood in a neutral state.

Cleaners containing Chlorine Bleach are commonly used to clean decks but they are not recommended for cleaning treated wood. Excessive use of chlorine bleach containing cleaners (sodium hypochlorite or calcium hypochlorite) can damage treated wood leaving it with an unnatural whitewashed appearance. Chlorine bleach also can raise the wood fibers and cause a fuzzy-looking surface.

Chlorine bleach (sodium hypochlorite) breaks down the lignin in wood causing excessive damage to wood cells. The natural pH of wood is slightly acidic, and bleach is a basic solution. As a result, use of bleach on wood shifts the pH from near neutral pH to a basic pH that will damage the cellular structure.

    • Bleach corrodes metal fasteners, screws and nails.
    • Bleach can cause damage to surrounding plants.
    • Bleach, after several months, lightens wood's natural color.
    • Bleach does not eliminate the spores from which mold and mildew grow

Bleach alternatives

  • Hydrogen peroxide is environmentally friendly and a safer substitute than bleach. Its chemical formulation is H2O2. As the oxidizing process releases the excess molecule of oxygen, H2O (water) remains as its residue. For tough jobs, hydrogen peroxide kills the mildew on contact within several minutes.
  • Oxygen bleach is sodium percarbonate, an environmentally friendly and excellent detergent and bleaching agent with a hydrogen peroxide base. Sodium percarbonate is a cleaning and bleaching agent with a strong fungicide effect. It has been tested and found to be more effective attacking the deeper-rooted organic growth on the porous wood surfaces.
    Sodium percarbonate is a white particle powder, nontoxic with no contamination, nonflammable, non-explosive, and soluble in water. It is also biodegradable and leaves no harmful by-products or residues that can harm the environment. Sodium percarbonate is effective in cleaning most average wood preparation jobs.
  • Sodium percarbonate is a chemical formulation is an adduct of sodium carbonate ("soda ash" or "washing soda") and hydrogen peroxide (that is, a perhydrate) whose formula is more properly written as 2 Na2CO3 · 3 H2O2.
  • Apply oxalic or citralic acid (deck brightener) after using sodium percarbonate or hydrogen peroxide in the cleaning process. The deck brightener will restore the wood to its natural pH and neutralize the sodium percarbonate cleaner. This will provide a beautiful finish when applying the final stain.
    The formula of oxalic acid is C2H2O4. Its usual form is that of the crystalline hydrate, (COOH)2·2H2O. Citralic acid is a specifically formulated blend of acids and surfactant and was designed to neutralize and brighten quickly without unwanted bleaching or damage to the wood. This is the step professional restoration contractors use to achieve that like-new look of fresh cut wood.

Download top rated deck cleaners according to consumer ratings in 2020.

Basic Deck Cleaning

There are a number of commercial products in the marketplace that are recommended for the cleaning of preservative treated wood decks. For best results always follow the manufacturer’s instructions. The following suggestions are provided as supplementary guidance. 

  • Clear the deck of all furniture, grills, etc., and the surrounding area of all debris and obstacles to create a safe work zone. 
  • Remove all debris trapped between deck boards and the edge of the house and sweep or blow the deck to remove all debris.
  • Prepare the surrounding area and protect your shrubs and plants with a plastic drop cloth. Spray water on plants in the surrounding area to dilute any over-spray of the deck cleaner that lands on desirable plants.
  • For mild stains and dirt use a mild dish detergent diluted in a bucket of water. Mop a small area of the deck surface with the detergent and then use a stiff bristle brush to work the dirt free from the surface.  Rinse the solution with a garden hose and re-clean areas as needed.
  • For more severe stains and dirt use a deck cleaner. Before use carefully mix/stir the product in accordance with the manufacturer's directions. Use eye protection and rubber gloves as directed.
  • Apply the deck cleaner according to manufacturer's instructions.
  • Unless directed otherwise by the manufacturer, apply the cleaner only to the amount of deck surface you can work at one time. Work in sections and let the deck cleaner do its work. Many cleaning solutions should not be allowed to dry on the wood so periodic spraying/misting may be required.
  • Let the cleaner set on the deck boards for the time period recommended by the manufacturer.
  • Once the cleaner has worked for the specified time, use a hard-bristled broom with synthetic bristles to scrub the deck clean. Scrub parallel with the wood grain at all times.
  • Rinse well with water and repeat the process on the next section of the deck. 
  • Once cleaning is completed inspect your work. The surface should be consistently clean and unmarred or damaged. Re-clean any stubborn areas that still look dirty.  

Power Washing Your Deck

Many homeowners want to use a power washer to clean decks but, without appropriate care, it is easy to ruin the deck surface and cause significant damage to the wood. Be especially careful power washing newer deck surfaces that have not been previously sealed or coated. If you do choose to use a power washer pay careful attention to the manufacturer’s instructions. In addition, these general recommendations obtained from various online sources may be helpful.

  • Use the lowest possible pressure that effectively cleans the surface.
  • Use a fan-tip only, set for an angle of spread between 40 and 60 degrees.
  • Never use a narrow stream or a rotating “tornado” type of tip.
  • Always start by pointing the spray away from people and glass windows and at least 24" away from the wood deck.
  • Once the fan spread is properly set, slowly begin feathering the spray approximately 18 inches from the deck.
  • Test your spray in an inconspicuous area and not the primary deck surface.
  • In general, avoid spraying closer than 16-20 inches unless the pressure is very low.
  • As you sweep the sprayer along the deck boards, many people will have a tendency to pivot their arm and that will create an inconsistent distance of the tip from the deck surface. Try to maintain a consistent distance from each deck board as you clean. You can do this by walking slowly and holding the sprayer steady at a level distance and angle.
  • Start cleaning deck boards closest to the house and work from the house outward to the far edge of the deck.
  • Work with the grain by feathering the spraying lengthwise with the deck boards and overlapping each area slightly. The objective is even cleaning with no visible differences on any board.

Cleaning Mold On Your Deck

Mold Growth

Mold and mildew are present everywhere in our environment, both indoors and outdoors. Mold and mildew need four things to thrive: air, water, temperatures between 32 and 120F, and a food source--  conditions that are common wherever humans live, work, and play. 

The best way to minimize mold and mildew growth is to control water and food sources. When it comes to mold or mildew on wood decking, water, and organic matter are the primary conditions that enable mold and mildew colonies to thrive. To minimize these conditions, make sure water has the ability to flow away from the deck surface and areas surrounding the deck to lessen the absorption of water. Ensure there is adequate ventilation between deck boards and underneath the deck surface, so water can rapidly evaporate.

And since both mold and mildew feed on dead or decaying organic matter, it is important to keep your deck clean of leaves and debris.

Tips for Minimizing Mold

  1. Maintain a deck that is dry and clean. 
  2. Ensure gutters/downspouts and dryer vents do not discharge directly on decks. 
  3. Ensure adequate ventilation under and between decking boards. 
  4. Minimize water puddles under decks and the use of wet mulch up against the deck structure. 
  5. Cleaning a deck just after the last of the major pollen events (when your car doesn't change color from the pollen anymore) will minimize the seasonal outbreak of mold and mildew. 
  6. Periodically rinse off your deck using a garden hose with a spray nozzle, especially after the major pollen events. Skilled professionals may use pressure washers with wide fan tips but in the wrong hands, your deck can be damaged. Exercise extreme caution when using pressure washers. 
  7. Ensure the gaps between the decking boards remain free of debris so that regular rain showers can remove pollen and organic debris between cleanings. 
  8. Avoid fertilizer over-spray. 

Staining and Sealing Your Project

A deck is a special part of your outdoor living space that should last for years. Keep it looking its best with the right deck cleaners, sealers and stains to enhance its long-term beauty.

Finishes

  • You can stain treated lumber when it is dry. Test the wood with a few drops of water to see if the wood is dry enough to readily absorb the water. Apply the stain to a small portion of the deck to ensure the wood is sufficiently dry. As soon as the wood is porous enough to accept the stain, it is ready to stain. Estimating exactly how long treated wood will take to dry is hard to predict and will depend on the time elapsed since pressure treatment, sun exposure, local temperature and recent weather conditions.
  • Apply a high-quality oil or water-based finish with UV protection to slow down the process of wood turning gray from exposure to the sun.
  • Apply a water repellent sealer at least every two years.
  • Always follow the manufacturer’s recommendations for new and re-application.

Safe Practices When Working With Pressure-Treated Wood

  • Wear appropriate safety protection when working with treated wood products including gloves, goggles and dust mask.
  • Wash hands thoroughly with mild soap and water after working with treated wood.
  • Do not burn pressure-treated wood or use treated wood debris as mulch.
  • Pressure-treated wood should not be used where it may come into direct or indirect contact with drinking water or a component of food, animal feed or beehives.
  • Dispose of treated wood debris in accordance with local regulations.