Home Improvement Ideas Decks Deck Building How to Clean a Deck to Remove Tough Stains and Grimy Buildup Learn how to remove stains on decks—including greasy spills, mildew, rust, and other grimy buildup—for a spotless outdoor space. By Jessica Bennett Jessica Bennett Jessica Bennett is an editor, writer, and former digital assistant home editor at BHG. Learn about BHG's Editorial Process Updated on April 21, 2021 Trending Videos Close this video player Decks play host to a wide range of outdoor activities during the warmer months. A season's worth of alfresco cooking, dining, and entertaining can easily dirty the surface with spots from grill grease, food or drink spills, soot from the firepit, and more. And because these spaces are exposed to the elements, they can naturally gather stains from dirt, leaves, tree sap, rusty furniture, and other grime throughout the year. Deck stains can be difficult to remove, but with the right cleaning method and supplies, you can get your outdoor space looking good as new. Keep in mind that the best deck stain remover will depend on the type of stain. Use the instructions below to learn how to clean a deck to restore your space for outdoor living. Aniko Levai How to Clean a Deck Plan to clean stains on decks as soon as possible to prevent the mark from setting into the wood permanently. In general, it's best to avoid using harsh chemicals to clean your wood deck. Chlorine bleach, for example, breaks down the wood fibers and can result in permanent damage to your deck or harm to the surrounding environment.To maintain your wood deck's good looks, reapply sealer or stain about every one to two years. Use these cleaning methods to tackle some of the most common deck stains. What You'll Need Equipment / Tools Barbecue Stains (Including Grease and Sauce) Stiff-bristled brush Damp sponge or mop Garden hose Candle Wax Credit card or putty knife Iron Wet rag Green Algae or Moss Scrub brush Mildew or Mold Commercial deck cleaner/brightener Stiff brush or broom Garden hose Tree Sap Scrub brush Materials Barbecue Stains (Including Grease and Sauce) Grease-cutting dish soap Hot water Candle Wax Brown paper bag or similar paper Green Algae or Moss Oxygen cleaner Borax Dish detergent One gallon water Leaf Stains Dish detergent Warm water Oxygen bleach (optional) Mildew or Mold Commercial deck cleaner Water Rust Dish detergent Warm water Oxygen bleach (optional) Tannin Stains Deck cleaner for tannin stains Tree Sap Murphy oil soap Water Instructions Barbecue Stains (Including Grease and Sauce) If your last backyard barbecue got messy, remove grease spots or saucy spills using a household dish detergent. Scrub the Stain Mix dish detergent designed to cut through grease, such as Dawn Ultra Liquid Dish Soap ($3, Target) with hot water. Using a stiff-bristled brush ($8, The Home Depot), scrub the area. Rinse the Area Use a dampened sponge to mop up the loosened grease. Rinse the area with a garden hose before it dries. Candle Wax Clean up candle wax following these steps. Scrape Away Wax To clear away wax drips from outdoor candles, first carefully scrape away as much residue as possible using a credit card, putty knife, or similar tool that will not gouge the wood. Warm the Wax Cover the area with plain paper (such as a brown paper bag) and use an iron set on low to gently warm the wax. The residue should lift away on the paper. Repeat until the wax is gone, replacing the paper as needed. Alternatively, you can clean candle wax off a wood deck using mineral spirits ($7, The Home Depot). Saturate a rag and set it on the dried wax until it absorbs the residue, rubbing lightly if necessary. Green Algae or Moss Spurred on by damp, dark conditions, algae and moss growth creates a slippery deck surface and can lead to wood rot or other permanent damage. These stains are difficult to remove and usually reappear once the roots are formed in the wood, so it's important to treat them right away. Mix Bleach Solution Remove green algae or moss stains on wood decks using an oxygen bleach solution. Mix together one cup oxygen bleach, 1/2 cup borax, and 2 tablespoons dish detergent in one gallon water. Scrub and Rinse Scrub the stained areas with a brush dipped into the solution, then wait about 15 minutes before rinsing with a hose. Leaf Stains When leaves accumulate on decks or porches, they can start to decompose and leave behind dark marks or silhouettes. You can avoid these stains by regularly clearing away leaves from your deck as they begin to fall. Scrub the Area To remove leaf stains on wood decks, scrub the area with a solution of dish detergent and warm water. Let Sit, Scrub and Rinse Let the cleaning solution soak in for about 15 minutes before scrubbing again and rinsing with a hose. For stubborn stains, try scrubbing with a solution of one cup oxygen bleach ($9, Target) to one gallon of water, repeating as necessary until the stains disappear. Mildew or Mold Mildew or mold is a common problem for decks in shady or damp areas, but regular cleaning can help keep it at bay. Some deck cleaners contain acids or chlorine, which can harm plants; check the label before using the product. Clean the Surface and Let Sit Clean the surface with a commercial deck cleaner/brightener ($16, The Home Depot). If it is not in liquid form, mix the powder concentrate with the recommended amount of water and apply with a garden sprayer, brush, or roller. Let sit for a few minutes. Brush and Rinse Brush briskly with a stiff brush or broom. Rinse with a garden hose. Rust Rusty outdoor furniture can leave red-brown rings or marks on your deck. Spray Deck and Wipe To remove rust stains, spray a 50-50 solution of water and distilled white vinegar on the stain and let sit for about 10 minutes before wiping clean with a cloth. For stubborn stains, try using an oxalic acid cleaner ($10, The Home Depot) following the manufacturer's instructions. Tannin Stains Tannins are naturally occurring compounds found in many trees and plants. They can sometimes cause dark stains to appear on wood decks after rain draws tannins to the surface. Use Deck Cleaner Remove the black streaks of tannin-rich woods with a specially formulated deck cleaner for tannin stains ($10, The Home Depot), following the manufacturer's instructions. Tree Sap Tree sap can harden on the surface of your deck, creating stains that are difficult to remove. Soften the Sap To soften the sticky residue, apply Murphy Oil Soap ($3, Walmart) directly on the stain. Scrub and Rinse Let sit for about 15 minutes, then scrub with a brush and rinse.