Pressure washers are powerful tools, but their intense water streams can do more harm than good on certain surfaces. Here’s a breakdown of what you should and shouldn’t pressure-wash based on advice from experts.

1. Decks

• Can Be Pressure-Washed:
• Composite decks (TimberTech, Trex): Light washing is usually sufficient, but check your warranty first.
• Hardwood decks (Ipe, Cumaru, Tigerwood): Hold up well.
• Pressure-treated wood: Generally safe if the nozzle isn’t too close.
• Tips: Use a low-pressure nozzle and test on an inconspicuous spot.
• Recommended Pressure: 800–1,000 psi

2. Roofs

• Avoid Pressure-Washing:
• The strong water stream can damage shingles and strip granules from asphalt shingles.
• Risk of loosening shingles or causing leaks.
• Alternative: Use a pump sprayer with a 50-50 bleach and water mix or mold-killing cleaner. Trim overhanging branches to reduce moss growth.

3. Driveways

• Can Be Pressure-Washed:
• Concrete driveways and walkways handle high pressure well.
• Use a finer nozzle for grease stains and lower pressure for mold or mildew.
• Recommended Pressure: 1,500–3,000 psi
• Pro Tip: Use a gas-powered washer for faster results.

4. Siding

• Sometimes Safe:
• Vinyl and fiber cement siding: Usually fine, but avoid spraying water into gaps around windows or doors.
• Wood clapboard siding: Safe if not painted with lead-based paint (common in homes built before 1978).
• Avoid shingle siding: Can knock shingles loose.
• Recommended Pressure: 1,200–1,500 psi

5. Cars

• Avoid Pressure-Washing:
• Can nick or damage the paint, potentially leading to rust.
• Alternative: Stick with a garden hose, soapy sponge, and elbow grease.

Pressure Washer Safety Tips

• Avoid 0-degree nozzles: These concentrated streams can damage surfaces and pose safety risks. Use at least a 15-degree nozzle.
• Wear protection: Safety goggles, gloves, and ear protection are essential.
• Stay grounded: Never use a pressure washer on a ladder—blowback can destabilize you.

Testing Criteria

• Pressure Output: Measures intensity (pounds per square inch).
• Paint-Stripping Test: Evaluates how quickly a washer removes paint.
• Noise Levels: Assessed to help users plan ear protection.
• Ease of Use: Features like automatic shutoff and easy fueling receive higher ratings.

Pro Tip: If a surface seems delicate or expensive to replace, test with the lowest pressure first. When in doubt, consider alternative cleaning methods.

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