How to Clean a Deck with Bleach

Loosening Surface Debris

Move all the furniture off of the deck. Furniture will get in the way as you clean. Remove all planters, seats, and tables from your deck before you start to clean it.

Sweep down your deck with a broom. Use a dry brush or broom to get the initial dirt and dust off of the deck. If you do this before you get the deck wet, it will be easier to remove grime and algae later. Work in large sweeping motions and go up and down your deck until it's free of debris and dust. You can remove debris like sticks, leaves, and seeds with a leaf blower. Additionally, you could use a shop vacuum to get in between crevices.

Spray down your deck with a hose to loosen dirt. Use a garden hose and spray in a uniform motion across the deck. If you have a pressurized attachment, you'll want to make sure that the pressure is not too high and not too low. Adjust the nozzle so that the hose creates a fan of water and not a single stream. If you don't have an adjustable nozzle, you can fit your thumb over half of the opening on the end of the hose to create a similar effect. If the pressure is too high on your hose, it can create discoloration on the surface of your deck.

Removing Algae and Dirt

Mix warm water and powdered oxygen bleach into a bucket. Pour 2 gallons (3.78 l) of warm water in a 5-gallon (18.92 l) bucket. Add 2 cups (400 g) of powdered oxygen bleach and mix the solution together using the sponge or brush that you'll be using to scrub down your deck. Continue to mix the solution until the components are well incorporated. Remember to wear water-proof gloves, boots, and possibly rain pants when working with bleach. Mix the solution outside or in a well-ventilated area.

Scrub down your deck with a synthetic brush or sponge. If you don't have a deck brush, you can use a large porous sponge to scrub down the surface of your deck instead. Liberally saturate the surface of the deck with the solution, then start scrubbing the deck until the solution starts to lather. Synthetic deck brushes can be purchased at most hardware stores and are designed specifically to wash a deck. Be careful when walking on your deck because the bleach solution will make it slippery.

Let the suds sit on the deck for 5 minutes. Letting the suds sit on the deck will allow the oxygen bleach to absorb the dirt and algae on your deck. It's important that you don't let the solution thoroughly dry on the deck, or it can leave a film on the surface.

Rinse down your deck. Use the hose to do a final rinse down of your deck. If you don't have a hose, you can get buckets of water from an indoor faucet and use that to rinse down the deck. Make sure that all of the bleach solution is rinsed away before letting your deck air dry.

Treating Mildew and Stains

Create an oxygen bleach paste to spot clean your deck. If you don't need to do a full cleaning of your deck, but you see an excess buildup of algae or dirt, you can make a more concentrated paste with your bleach. Simply add a little water to some oxygen bleach powder and mix the solution together with a spoon until it forms a thick paste. Apply the paste to the dirty areas of your deck with a nylon brush and let it sit for 15 minutes before thoroughly rinsing it off.

Add borax to your deck cleaning mixture to remove mildew. Pour one cup (200 g) of borax into the bucket with your bleach and water solution. Mix it together while wearing gloves and target specific areas on your deck where mildew has formed. Borax can typically be found in the laundry detergent aisle of the grocery store and is a mineral compound that won't destroy your nearby plants.

Don't use power washers or chlorine bleach to wash your deck. Power washers can sometimes be too powerful and could damage the wood forever. Instead of using a power washer, use a pressurized adjustment on your hose or a lighter pressure spray machine. Never use chlorine bleach to wash your deck. Chlorine bleach is toxic to plant life, can discolor your wood, and reduces the integrity of the wood.