What Not to Power Wash Around Your House

There's something satisfying about a pressure washer. Point it at a grimy driveway and a clean stripe appears in seconds, and before long you're looking around for the next thing to blast.

That's usually when the damage happens. Power washing your house goes a lot better when you know what not to power wash, and which surfaces can only take a low setting. Even the test engineer who oversees Consumer Reports' pressure washer ratings says using one on just about everything around the house isn't always a great idea.

What Not to Power Wash

Put the wand down for these.

• Asphalt shingle roofs. Consumer Reports says no. The spray can loosen shingles and strip away the granules that help them last, and running a pressure washer from a ladder is dangerous because the kickback can throw you off balance.
• Windows. Andersen, the window maker, advises against pressure washing because it may damage parts of the window.
• Screens. JELD-WEN's care guide says not to use chemicals or pressure washers on its screens. Mild soap, water and a soft brush will do.
• The air conditioner. Trane says not to use a power washer, or even the jet setting on a hose, because the force can bend or damage the coil fins. A gentle spray from a garden hose is enough.
• The gas meter and regulator. Enbridge Gas warns that water dripping on the meter, regulator or appliance vents can freeze, cause damage and create a safety hazard, so keep the spray well away from them in the fall.
• Wood shingle siding. The pressure can knock the shingles loose.

Test Old Paint Before Power Washing Your House

If your house was built before 1990, find out what's in the paint before you wash it. Health Canada says a home built before 1960 probably contains lead-based paint, and one built between 1960 and 1990 may have it on the exterior.

Pressure washing flaking paint knocks chips loose. Consumer Reports warns that lead paint washed off a house settles into the soil, where children playing outside can kick it up or track it indoors.

Health Canada says you can send paint chips to a lab, or hire a contractor with x-ray equipment that detects lead on painted surfaces. If the result is positive, talk to someone who handles lead paint safely before anything gets washed or scraped.

Surfaces That Need a Light Touch

Plenty of exterior surfaces can be washed. They just can't take full pressure. Concrete driveways and walkways are the exception, and Consumer Reports says they handle a powerful cleaning without etching. For the rest:

• Wood decks and fences. Softwood like pressure-treated pine etches if the nozzle gets too close. Consumer Reports suggests 800 to 1,000 psi for decks, starting with a low-pressure nozzle in a spot nobody will see and working along each board with the grain.
• Composite decking usually comes clean with a scrub brush and a hose. If you do pressure wash it, check the warranty first so you don't void it.
• Siding. Vinyl and fibre cement usually handle pressure washing fine, and Consumer Reports lists 1,200 to 1,500 psi for siding. Aluminum dents, so start at the lowest setting with a wide nozzle. With any siding, don't spray up under the laps or into gaps around windows and doors, where water can get trapped behind it.
• Brick. The Brick Industry Association says high-pressure water (over 800 psi) isn't appropriate for brick, and too much pressure can erode mortar joints and damage the surface. For rinsing, it recommends staying at or below 400 psi at the nozzle unless the brick maker allows more, with a wide fan tip held at least 12 inches back.

Pressure Washer Safety

The machine can hurt the person holding it too.

• Throw out the 0-degree nozzle, usually the red one. Consumer Reports recommends against it because the stream is concentrated enough to pierce surfaces, protective boots included.
• Wear safety goggles, hearing protection, gloves and sturdy footwear.
• Never use a pressure washer from a ladder.
• Fix loose or damaged siding before you wash so water doesn't get in behind it.
• Keep the spray off outdoor outlets and light fixtures.

When to Call a Pro

If the job involves a second storey, brick, older paint or a deck you plan to stain, it can be worth having someone who sets the pressure for each surface. We use commercial-grade equipment with adjustable pressure and protect plants and gardens from overspray. Heavy mildew, algae and oil stains get pre-treated before we wash.

Power washing has a $150 minimum. A standard two-car driveway usually costs $150 to $250, a full deck $150 to $300, and siding on a typical home $250 to $500. Doing a few areas at once saves money, so ask about a package quote.

Call (289) 928-5689 for a free written estimate.