Can you pressure wash stain off a deck?

Pressure washing is an effective way to remove stains from wooden decks. The high-powered stream of water can easily blast away dirt, mildew, mold, and other stubborn stains. With the right pressure washer and technique, you can restore your deck to looking like new.

What causes stains on wooden decks?

There are several common causes of stains on deck boards:

• Mold and mildew – Wet, shady areas allow mold and mildew to grow, leaving black or green stains.
• Dirt and grime – Normal foot traffic brings dirt that gets ground into the wood.
• Weathering – Years of exposure to sun, rain, and snow take their toll on the deck boards.
• Spills – Food, grease, oil, and iron stains from metal furniture can occur over time.
• Leaf tannins – Decaying leaves that sit on the deck can leave tan or brown stains.
• Wood rot and fungus – Unmaintained decks develop dark gray or black stains from rot and fungus.

Knowing the source of the stains on your deck will help determine the best way to remove them.

Preparing to pressure wash

Proper preparation is key to successfully removing stains from your deck with a pressure washer. Here are some tips to get your deck ready:

• Clear the deck – Remove all furniture, planters, rugs and other items from the deck so you can access the entire surface.
• Inspect the deck – Look for cracked or damaged boards that may need replacement after cleaning.
• Repair any damaged boards – Fixing broken boards first prevents further damage during pressure washing.
• Check the foundation – Make sure the support structure is intact without sagging or unstable joists.
• Fill cracks – Caulk or use wood filler to fill cracks and crevices so they don’t expand during cleaning.
• Wet down the deck – Use a garden hose to lightly pre-soak the deck before power washing.

Taking these steps allows for more effective stain removal and protects your deck during the pressure washing process.

Choosing a pressure washer

Selecting the right pressure washer for deck cleaning is very important:

• Gas pressure washer – More powerful, best for large decks with heavy stains.
• Electric pressure washer – Portable and easy to maneuver, good for smaller decks.
• Cold water unit – For most deck cleaning, cold water is sufficient.
• Hot water unit – If stains are heavy, choose a hot water model for better cleaning.
• PSI of 1500-4000 – Look for a PSI of 1500 for light stains, up to 4000 PSI for tougher stains.
• Nozzle spray tips – A fan tip nozzle is the most effective for deck stain removal.

Consult a home improvement retailer for recommendations on the ideal pressure washer system for your needs. Purchase or rent a pressure washer that can handle the size of your deck and type of stains present.

Setting the pressure washer

It’s important to set up your pressure washer properly before beginning to clean the deck:

• Use safety gear – Wear eye and ear protection, closed-toe shoes, gloves, and long pants.
• Position the washer – Place it on a level surface near a water source and the deck.
• Attach the hose – Connect the washer hose to your spigot or outdoor faucet.
• Determine technique – Decide if you’ll work left-to-right or use an up-and-down motion.
• Test a small area – Try a practice run on a hidden spot before tackling the whole deck.
• Adjust pressure – Increase or decrease as needed based on stain removal.
• Use stain removal tips – Try spray detergent, chemical cleaners, or degreasers if needed.

Making adjustments to find the ideal pressure washing setup will give you the best final cleaned deck outcome.

Pressure washing technique

Proper technique is critical for removing stains without damaging the deck:

• Keep spray nozzle moving – Don’t concentrate on one area too long or hold it stationary.
• Use just enough pressure – Excessive pressure can splinter or scratch the deck boards.
• Maintain consistent distance – Hold the nozzle 12-18 inches away as you spray the cleaning path.
• Work in manageable sections – Clean a few boards at a time until the entire deck surface is complete.
• Overlap passes – Each cleaning pass should overlap the previous one to ensure even coverage.
• Blast away debris – Occasionally blow away loosened debris with the spray nozzle.
• Target stubborn stains – Lightly scrub extra dirty spots with a stiff brush if needed.
• Rinse with care – At the end, do a final gentle rinse to wash away any chemical residue.

Applying these proper techniques provides optimal stain removal while protecting the condition of the wood decking.

Cleaning products for extra stain removal power

If plain pressure washing fails to remove all the stains, using cleaning solutions can offer extra power:

Product	Uses
Oxygen bleach	Removes gray weathered wood, leaf tannins, iron stains
Sodium percarbonate	Brightens weathered wood, eliminates mildew stains
Oxalic acid	Bleaches and restores grayed wood fibers
Deck cleaners	Designed for wood stain removal without damage
Household bleach	Kills and removes mildew, mold stains

Mixing one of these cleaning solutions in a pump spray bottle and applying to the deck before pressure washing gives the added stain-fighting capability that may be needed for difficult deck stains.

Finishing the pressure washing job

Once you’ve completed the pressure washing of the deck, there are a few final steps to take:

• Inspect the surface – Check for any remaining stains that may need spot treatment.
• Rinse away residue – Do a final light spray of just water to clean any chemical residue.
• Allow to dry – Let the deck dry out completely before applying any sealants or stains.
• Apply wood brightener – Using a brightener helps restore a freshly cleaned look.
• Seal or stain – Consider applying sealant or wood stain to protect and beautify the cleaned deck.
• Replace damaged boards – Use the opportunity to replace any boards in poor condition.
• Clean pressure washer – Thoroughly clean the unit after use to maintain it for future jobs.

Completing the entire pressure washing process from start to finish will revitalize your deck and keep it looking clean and vibrant for the next season of use.

Tips for maintaining a clean deck

After putting in the hard work to pressure wash your deck, keep it looking fresh by following these maintenance tips:

• Sweep often – Frequent light sweeping keeps dirt from building up.
• Spray off spills – Don’t let food, grease or other spills soak in.
• Re-seal yearly – Apply new sealer before winter and summer seasons.
• Power wash twice a year – Schedule spring and fall cleanings.
• Remove leaves – Don’t let leaves accumulate to cause leaf tannin stains.
• Keep wet areas dry – Improve drainage and ventilation to prevent mold and mildew.
• Re-coat stain – Re-stain walks areas every 1-2 years as needed.
• Clean under furniture – Move pots, benches and other items to clean underneath.

By dedicating a little time each week and season to care for your deck, you can keep it looking clean and vibrant for years to come after pressure washing.

When to call a professional

In some cases, it may be worth hiring a professional pressure washing service for your deck:

• Extremely large deck
• Multiple levels or tricky layout
• Heavily damaged wood needing replacement
• Severe mold, mildew or fungus growth
• Tough stains that resist cleaning solutions
• Concerns over moisture damage if not dried properly
• Don’t own or can’t operate needed pressure washer
• Want to ensure a deep, flawless cleaning

Pros have the experience, tools and techniques to tackle the most challenging deck staining jobs and preserve the quality of the wood. Get an estimate to decide if hiring help is worth the investment.

Conclusion

Pressure washing is an effective method for removing stains from deck boards and restoring a like-new appearance. With the proper pressure washer, setup, cleaning technique, and maintenance, you can eliminate stains caused by mold, mildew, dirt, weathering, spills and other common deck damage. Following safety precautions and taking care not to damage the wood will allow you to successfully pressure wash away deck stains yourself. For extremely large or challenging decks, hiring a professional can be the best solution to get optimal cleaning results.