You should avoid using a pressure washer on any surface or item that could be damaged by the high-pressure spray, as some materials are too delicate to withstand the force.

Key items and surfaces to avoid include:

• Electrical Components: Never pressure wash electrical systems, as water can cause short-circuits and create a safety hazard. This includes utility meters, breaker boxes, electrical outlets, generators, and HVAC or air conditioner units.

• Delicate and Fragile Materials: Fragile items can crack, shatter, or be stripped by the pressure. Avoid pressure washing windows, glass, light fixtures, shingled roofs (especially asphalt), and stucco.

• Painted, Stained, or Sealed Surfaces: Unless your goal is to strip the finish, do not pressure wash painted surfaces, stained wood (like decks), or anything with a protective seal that could be stripped away. Be especially cautious with older surfaces that may contain lead paint.

• Soft Woods and Certain Decking: Delicate surfaces like softwood, composite decking, and antique or wooden patio furniture can be etched or damaged. If you must wash wood, use a lower-powered pressure washer with a wide-angle nozzle to prevent damage.

• Living Things: Never use a pressure washer on people, pets, or plants. The force can cause serious injury and will destroy landscaping.

The best time to clean the outside of your house is during your outdoor spring cleaning. Wait until late spring, after the wave of pollen is done coating your home. You can also wash your house in late fall–before the first freeze–to remove leaves and branches from the gutters.

You can use a pressure washer to clean a whole host of surfaces. The exterior siding of your house is one of the most popular spots, as well as your driveway, garage floor, patio or deck, and even your outdoor furniture. Just be mindful about the amount of pressure you apply to different materials—concrete can handle a lot more than wood, for example.

It is possible to wash your own roof, but we don’t recommend it. First, getting up on any roof is dangerous without proper safety equipment, especially if wetting a metal roof and making the surface slick. Additionally, it’s easy to damage your roof or force water between roof seams if you use a power washer, which can lead to property damage. Hiring a professional roof cleaner will save you time, keep you safe, and ensure that your roof looks new again without damaging it in the process. Plus, roof cleaning is a relatively affordable home improvement project.