How to Properly Clean a Deck

Cleaning a deck helps to protect it from rot and staining. It is important to thoroughly clean your deck, including stairways and railings, once or twice a year.

Start by sweeping your deck regularly, preferably daily, with a push broom or a leaf blower. Next, apply a nontoxic oxygen bleach solution to kill mildew and other fungi. Finish up by applying a wood brightener to restore the natural pH of the wood and rinse. Read on to know more.

Debris Removal

If your deck is overgrown with leaves, twigs, or dirt, sweep it regularly. This will prevent moisture from gathering under the debris and staining your deck.

Make sure your cleaning supplies are compatible with your deck’s material and the type of stains you’re trying to remove. A general-purpose cleaning solution such as a mild detergent and warm water can help to remove most dirt, but more severe stains may require the use of a cleaner specifically formulated for wood or for tannin stains (commonly black marks caused by decomposing leaves) on a deck made from alder, cedar or redwood.

If your deck is prone to mold or mildew, use a special wood cleaner with bleach to scrub the surface and then rinse thoroughly. A pressure washer can speed the process, but you’ll need to be careful to avoid damage to the boards or any plants surrounding your deck. Oxygen bleach ($9, Target) can be used as an eco-friendly alternative to chlorine bleach and is effective for removing mildew and algae from decks.

Stains and Mildew Removal

A good cleaning will remove mildew and staining from your deck. If you’re dealing with a really bad stain, mix a paste of OxyClean with a bit of water and scrub the area with a stiff bristle brush. Rinse well.

For general mildew and dirt, use a mild dish detergent diluted with water. It’s also a good idea to sweep regularly and frequently to keep the deck clean and prevent dirt and debris from getting ground into the wood.

Black mold (Stachybotrys chartarum) is another common concern. This fungus can cause respiratory problems, skin irritation, and other health issues.

Regular light sweeping will help to avoid black mold. For a more serious problem, use a product that targets the fungus such as Wet & Forget Xtreme Reach Hose End. Be sure to read the label and follow the instructions carefully. It’s important to protect plants and shrubs around the deck from over-spray from these products.

Pressure Washing

Before you start cleaning, remove containers, furniture, and any other items you don’t want to be damaged by the pressure washer. Also, cut back any plants that are overhanging or could get sprayed with the cleaner. Finally, sweep the deck thoroughly and dispose of the debris in a trash can.

There are many different types of deck cleaners available, and it is important to read the label carefully. Some require rinsing after application, while others are designed to remain on the wood surface to saturate the decking with mold- and algae-fighting ingredients.

Chlorine bleach-containing cleaners should not be used on treated wood. The chlorine leaches out the natural oils in treated lumber, leaving it with an unnatural whitewashed appearance and causing damage to metal fasteners, screws, and nails. It also irritates skin, eyes, and mucous membranes. The best choice for a deck cleaning chemical is a biodegradable, non-toxic bleach. There are many of these products on the market, including OxiClean and Wet & Forget Moss, Mildew, Mold & Algae Cleaner.


After a winter of snow and rain, decks need to be prepped for summer entertaining. The first step is to give the deck a thorough cleaning. Before starting the process, remove all furniture and coverings (leaving them on a wet deck can damage the surface) and sweep the entire area. This will get rid of a year’s worth of debris and splinters.

Be sure to inspect the joists, posts, and stair stringers for pest damage. Also, test the wood for rot by tapping it with a screwdriver. If it feels soft and has a mushy sound, then the wood is probably rotten and needs to be replaced.

There are many commercial products that can help remove stains from a deck. Most contain a bleach ingredient that can damage the wood, so be sure to rinse thoroughly after using them. If the stain is from rust or iron, use table salt or lemon juice to treat it before cleaning the deck. Check out this interesting post!