For cleaning walkways and sidewalks and stripping old paint from a deck, nothing compares to a pressure washer. Its unbridled power blasts away grime in no time.

So you might be inclined to pressure wash just about everything around the house, but that's often not a great idea. The supercharged stream of water from a pressure washer can damage paint and nick or etch wood and some stones. In some cases, using a pressure washer is overkill when a simple scrubbing and hose down would have sufficed.

So should you pressure wash your deck, siding, roof, car, or driveway?

Cement Walkway and Driveway

Should you pressure wash it?
Yes.
Cement can readily withstand a powerful cleaning without much concern over etching. Generally, a finer nozzle will prove more effective at spot cleaning grease stains, but moldy or mildew-covered cement is best coated in suds first using lower pressure. The Cub Cadet CC3224, $500, is among the most powerful models in our ratings, but it includes a 0-degree tip, which we advise discarding if you buy this unit (see "Pressure Washer Safety," below).


Before you shop for a new pressure washer, check our buying guide and ratings of gas and electric pressure washers.
 

Deck

Should you pressure wash it?
Yes.
Decks made from South American hardwoods such as Ipe, Camaru, and Tigerwood will hold up to the pressure just fine. Decks made of pressure-treated wood are usually okay, too. Pressure-treated wood is usually southern yellow pine, which is pretty soft, so start with a low-pressure nozzle on an inconspicuous spot to make sure you don’t etch or mark the wood. Then work along the length of the board, with the grain of the wood. For this job we recommend the Greenworks GPW1951, $189, which offers effective cleaning at an excellent value. 

Not all decks need to be pressure-washed. Newer composite decks often resist staining in the first place, or can be cleaned with a light scrubbing.

Siding

Should you pressure wash it?
Sometimes.
Vinyl siding is pliable and can typically withstand pressure washing without much concern. The same goes for fiber cement siding. Aluminum siding, however, can dent, so it’s best to start on the lowest pressure setting with a broad nozzle, and use more concentrated blasts only for problem spots.

Wood clapboard siding can be effectively washed, too, but if your house was built before 1978, have the exterior paint tested first by an EPA-licensed lead-remediation specialist. If you knock old lead paint loose, it will land in your soil and never break down because lead is a heavy metal. Don’t power wash any shingle siding—the pressure can knock them loose.  

Roof

Should you pressure-wash it?
No.
Tempting as it might be to blast away unsightly moss and algae, using a pressure washer on your roof is dangerous and potentially destructive. For starters, we never recommend using a pressure washer on a ladder because blowback could cause you to lose your balance. The powerful stream of water can also knock shingles loose and strip them of the embedded granules that help extend the life of your roof.

Instead, spray the roof down with a cleaner that kills mold and moss or apply a 50/50 mixture of bleach and water and let the moss die on its own. Removing excess shade by trimming overhanging branches or cutting down trees will allow sunlight to hit your roof and prevent the moss from growing in the first place.  

Car

Should you pressure wash it?
No.
Plenty of people do, but it can do more harm than good. A car wash usually gets the job done just fine—so does a garden hose and soapy sponge. Using a pressure washer can damage or nick the paint, which could lead to rust down the road. Instead, use a little elbow grease and a specialized cleaner on problem spots such as wheels.


Pressure Washer Safety

Pressure washers come with nozzles ranging from 0 degrees to about 40 degrees. The higher the number, the wider the spray pattern and the less concentrated the stream of water. Consumer Reports recommends against using a 0-degree nozzle because it poses an unnecessary safety risk. Water concentrated to such a fine point can pierce protective boots.

If your pressure washer came with a red 0-degree nozzle, dispose of it properly. The next size, a 15-degree nozzle, will do just fine. And always wear hearing protection, protective footwear, and gloves while you work.

Pressure Washing Tips