Like all products that are exposed to the outdoors, a deck top of Cedar (as well as any other wood or manufactured decking) will become dirty and require some routine maintenance. A deck that is kept free of dirt and debris, both on the deck surface as well as underneath to allow airflow, will last longer and look better.
Annually, your deck should be inspected thoroughly and cleaned for optimum results, whether you plan on re-staining it or allowing it to go naturally grey.
Start by giving your Cedar deck a good sweeping and remove any leaves or other debris underneath the deck. Depending on how dirty the deck is, you can use a pressure washer fitted with a fan tip to loosen any stuck-on dirt if needed. Be sure to set the pressure to around 500 psi to 600 pounds per square inch (psi); any higher could cause the grain to come up or cause damage to the decking boards.
While there are many deck cleaners available on the market, we have found a solution of warm water, TSP (trisodium phosphate), and a small amount of bleach (or powdered oxygen bleach like Oxiclean) to work really well and be very cost-effective. Spray the solution on with an inexpensive garden sprayer, let sit about 5 minutes, scrub with a soft bristle cleaning brush where needed, and then rinse with thoroughly water. This should bring the Cedar deck top back to almost new condition. For help with specific problems or stains, check out our blog on those by clicking HERE.
We supplied the Clear, Western Red Cedar decking for this project a little over a year ago. Our customer just recently gave it an annual good cleaning, and as you can see, the deck top is brought back to “like new” condition.
The surfaces of finished Western Red Cedar decks, siding, and trim boards exposed outdoors inevitably become dirty and may also be discolored by mildew, algae, and moss. These natural elements slowly erode any previously applied finishes, and as a result, all exterior cedar requires regular cleaning and maintenance to perform and look its best. The degree of maintenance required depends on local conditions, the type of finish used, and the end-use of the cedar building materials.
DISCOLORATION OF FINISHES ON WESTERN RED CEDAR
Western Red Cedar enjoys a well-deserved reputation as a wood that takes and holds a range of finishes for extended periods. Nevertheless, a finish’s usual lifespan will be shortened by degradation and discoloration. The causes of discoloration often require a remedial treatment.
DIRT
Dirt is the most benign cause of discoloration. A periodic cleaning with a mild, non-phosphate detergent solution will usually restore the surface finish.
MILDEW
Mildew is a common form of discoloration of paints and stains caused by staining fungi. Re-staining does not solve a mildew problem. When it is time to refinish, clean off the mildew with a mild bleach solution (oxygen bleach is preferred) or commercial mildew remover. After the wood has been thoroughly rinsed and allowed to dry, refinish with a coating that contains an effective mildewcide.
Tip: A simple test for the presence of mildew on the coating can be made by applying a drop or two of a fresh solution of liquid household bleach (containing 5 percent sodium hypochlorite) to the stained area. The dark color of mildew will usually bleach out in 15 to 30 seconds. Discoloration that does not bleach is due to other factors and requires further investigation.
EXTRACTIVE BLEEDING
Discoloration due to extractive bleeding is usually caused by moisture. To stop stains caused by extractive bleeding, the moisture source must be eliminated. Mild staining is often washed away by rain over a period of weeks. In sheltered areas of a building where the stain persists, it may become darker with age and more difficult to remove. If washing with a mild detergent solution does not work, applying a mild oxalic acid solution has been proven to be effective in removing water, tannin, or iron stains. Commercial cleaners are also available if the stain remains; prime the area with an alkyd primer and topcoat with a latex coating.
IRON STAINS
Iron stains may appear in two forms: the reddish-brown discoloration caused by rust or blue-black discoloration caused by the reaction of iron from nails and other metal objects with extractives from the Western Red Cedar. To prevent these stains, use only hot-dipped
galvanized, aluminum, or stainless steel nails when fastening cedar. To clean areas affected by iron stains, use a commercial cleaner from your local home building center. In situations where the stain has penetrated the wood surface, light sanding or brushing may be required.
WATER STAINS
Water stains often occur in combination with extractive bleeding and mildew growth. These stains can be difficult to remove. Scrubbing the cedar with a dilute oxalic acid solution is sometimes
effective.
Caution: Handle oxalic acid solution with care as it can be harmful – carefully follow the
instructions.
CHALKING
Chalking, the release of pigment and degraded resin particles, results from weathering of the paint’s surface. It is a degradation of the paint film, not the cedar. Chalking is a common cause of fading in tinted or colored paints.
PEELING, BLISTERING OR FLAKING
Paint failure such as peeling, blistering, or flaking is often associated with moisture build-up behind the paint and poor adhesion of the paint film to the underlying wood. This problem is exacerbated if the paint is applied to weathered wood.
REGULAR MAINTENANCE EXTENDS THE LIFE OF BOTH FINISH AND DECKING
A deck that dries after wetting will last longer than one that stays damp. Ongoing maintenance practices for cedar decks include: allowing proper water drainage; keeping the surface free of dirt, leaves, tree needles, and other debris; moving planters, benches, and other deck accessories from time to time to permit the deck beneath them to dry thoroughly and ensuring that the ventilation under the deck is not inhibited.
