How To Clean A Deck?
QUICK ANSWER
Sweep all debris from the deck. Apply a deck cleaner (Olympic Deck Cleaner, Wet & Forget, Krud Kutter Deck Wash) with a stiff brush or pump sprayer. Let dwell 10 to 15 minutes. Scrub gently along the grain. Rinse with a garden hose. For mildew, add bleach or use an oxygenated cleaner.
Decks accumulate dirt, mildew, leaf stains, pollen, and weathering over time. Cleaning extends deck life dramatically and is required before any staining or sealing. Wood and composite decks need different approaches. Pressure washing can damage wood; gentle chemical cleaning is safer for both materials. Here is the right method for each deck type plus how to prep a deck for staining when the goal is more than just appearance.
What is on your deck?
Common deck issues each need slightly different treatment. General dirt and pollen: standard cleaning with deck cleaner handles this. Green mildew or algae: needs cleaners with mildewcide (oxygen bleach or chlorine bleach). Black mold spots: more severe than mildew; needs stronger bleach treatment. Tannin stains (dark spots from leaves): need oxalic acid-based cleaners specifically formulated for tannin. Tree sap: needs solvent treatment; rubbing alcohol or mineral spirits. Grease and food stains: dish soap and hot water. Bird droppings: dish soap and water; for old stains, oxalic acid cleaner. Identifying the issue helps choose the right cleaner.
What is the basic method for wood decks?
Sweep the deck thoroughly to remove leaves and dirt. Wet the surrounding plants and grass since cleaners can damage plants. Apply a deck cleaner per the product label: Olympic Deck Cleaner, Wet & Forget Outdoor, Cabot Problem Solver Wood Cleaner, or a DIY mix (1 cup oxygen bleach plus 1 gallon warm water). Use a pump sprayer for even coverage or a stiff brush for application. Let dwell 10 to 15 minutes; don't let dry on the wood. Scrub gently along the wood grain (across-grain scrubbing roughens the surface). Rinse thoroughly with a garden hose.
How is composite deck cleaning different?
Composite decks (Trex, TimberTech, AZEK) are more stain-resistant than wood but still need cleaning. Use the manufacturer's recommended cleaner (Trex Deck Cleaner, etc.) or a mild dish soap solution. Avoid: acidic cleaners which can damage some composites, strong solvents, and abrasive scrubbing. For mold and mildew on composite: oxygen bleach (OxiClean Versatile) plus warm water, applied with a soft brush. For oil and grease: dish soap and warm water; treat fresh stains quickly before they set. Pressure washing on composite: use low pressure (under 1500 PSI) only; high pressure damages the surface texture.
Should you pressure wash?
Pressure washing wood decks is risky; the water pressure can splinter the wood fibers, raise the grain dramatically, and shorten the lifespan of the deck. If you do pressure wash wood: use 25 or 40-degree nozzle (never narrower), under 1500 PSI, hold the wand 12+ inches from the surface, move steadily without dwelling in one spot. After pressure washing wood, the surface needs sanding before any stain or sealer. For composite decks: pressure washing is generally fine at low pressure with proper technique. For both: chemical cleaning followed by manual scrubbing usually gets better results without damage.
Deck cleaning prepares the surface for sealing or staining and maintains appearance and longevity. Wood decks need gentle chemical cleaning; composite decks tolerate similar treatment with manufacturer-recommended cleaners. Pressure washing can damage wood; use carefully if at all. Annual cleaning is appropriate for most decks; twice yearly in shaded or humid environments. For severely weathered decks, professional cleaning combined with refinishing restores appearance dramatically.
More Roof, Siding & Exterior Questions
Mystery Question?
Mystery Question?
Mystery Question?