Fall cleanup can be a breeze with a pressure washer. But experts warn you should think before you spray.

“It’s really easy to overdo it with a pressure washer but you have to remember they can chip paint, dent wood and even etch stone,” said Paul Hope, Consumer Reports home editor.

To keep things safe, Consumer Reports says to start by getting rid of the zero degree nozzle. The pinpoint blast from the zero degree nozzle can rip apart a glove or work boot.

“We think zero degree nozzles pose a totally unnecessary risk, so if you buy a pressure washer that comes with one we suggest throwing it out,” explained Hope.

Once the nozzle is gone, you can start thinking about which surfaces are safe to clean.

One place to avoid is the roof.

“It’s not a great idea to use a pressure washer on your roof because it’s dangerous. The kickback could cause a ladder to fall backwards. Plus, you end up doing more harm than good to the roofing shingles,” Hope said.

Instead, spray the roof down with a 50-50 mix of bleach and water and let any moss die on its own.

Wood and siding made of vinyl and fibre cement can typically hold up with pressure washing. But you should use caution with aluminum siding. Aluminum siding can actually be easily dented, so if you’re going to try to pressure wash, it start on the gentlest setting then work your way up.

Concrete and asphalt walkways and driveways can stand up to the power. For mouldy mildew use lower pressure and some suds. To tackle grease stains you’ll need a finer, more targeted stream.

You can also pressure wash most decks. Start with a lower pressure nozzle to make sure you don’t etch or mark the wood, but you might not even need to. Newer composite decking actually resists staining and mildew so you probably don’t even need to clean them with a pressure washer. Generally a light scrubbing will do.

Wherever you are cleaning, remember to wear safety goggles and protective shoes, and never point the pressure washer at a person or your pet.