9 Things You Should NEVER Pressure Wash

Pressure washers are powerful tools that can drastically transform the look of your home’s siding, driveways, and even cars (when done carefully, of course). But, “it’s just as important to know what not to pressure wash,” says Dylan Fox, product development manager at Greenworks.

Certain items and materials should never be subjected to pressure washing, as strong water jets can cause costly repairs, safety hazards, or irreversible damage. “Softer materials like stucco, soft woods, and aluminum siding require a gentle touch,” Fox says. So, before you get carried away with your machine, keep reading to find out which things you should never pressure wash and why.

1. Roofs and (Some) Siding

Whether they’re made of asphalt, tile, slate, metal, or wood, roof tiles are not a good candidate for pressure washing. Sure, the roof gets dirty as it’s exposed to the elements. But the force of the jet can knock them out of place and create opportunities for leaks. It can also remove protective coatings, which will shorten the lifespan of your roof. And, as all homeowners know, replacing a roof is a significant expense! It’s best to leave roof cleaning to professionals with specialized equipment, especially if you have solar panels installed, to ensure the structural integrity stays intact.

And while it’s perfectly safe to pressure wash some siding, there’s one material you should always steer clear of. “Fiber cement siding is best left out of the pressure washing routine entirely, as cleaning it with high pressure may void manufacturer warranties,” Fox says.

2. Gutters

Sitting right below the roof, gutters can technically be pressure-washed. However, it’s strongly advised to refrain from doing so. High pressure can loosen gutter joints, damage brackets, and even fully detach the gutters from the sides of your home. To clean gutters, it’s best to remove debris by hand and flush them with a gentler method, such as a garden hose.

3. Old Brick Surfaces

While it’s generally OK to pressure wash brick walls and patios, if the mortar keeping the bricks together is old, you’ll be doing more harm than good. The jet stream can cause it to deteriorate or crumble faster, which can lead to structural issues. If you can’t stand the thought of scrubbing your home’s visibly dirty brick exterior walls and want to use the pressure washer, be sure to use your machine’s lowest PSI (pounds per square inch) setting and steer clear of spraying the mortar joints. “The key is matching pressure and nozzle size to the material,” Fox says.

4. Painted or Stained Surfaces

Unless you plan to repaint or restain the surface in the near future, avoid pressure washing it. Blasts of water can strip away the paint or stain, resulting in uneven patches and exposing the underlying material to the elements. If, in the unlikely event, paint contains lead, pressure washing can actually dislodge the particles into the air and nearby soil, creating a health hazard. If you need to clean a painted or stained surface, it’s best to use soapy warm water, a non-abrasive sponge or cloth, and a bit of elbow grease.

5. Glass Doors and Windows

Glass surfaces, particularly older or single-pane windows, can crack or shatter when exposed to high-pressure water streams. Furthermore, pressure washing can damage the seals around windows, leading to drafts and water leaks. For cleaning windows, it’s safer to use a gentler cleaning method, such as a squeegee and a suitable cleaning solution, like a DIY vinegar spray.

6. Light Fixtures

Outdoor lights typically contain seals to protect against rain; however, these seals are not built to withstand the high pressure of a pressure washer. If strong water forces penetrate these seals, it can result in electrical failures or corrosion. To clean outdoor lights safely, turn off the power and simply use a damp cloth to wipe them down.

7. Electrical Components

Needless to say, anything on the exterior of your home that contains electrical parts shouldn’t be touched with the stream of a pressure washer. This includes your HVAC unit, generator, meters, and electrical panels. The force of water can cause numerous issues, such as bending air conditioner coils and causing short circuits or power outages. In a worst-case scenario, it can cause a fire, so it’s clearly not worth the risk.

8. Some Pool Materials

For most pools, the area surrounding them can be pressure-washed, and even some empty pools themselves can withstand the force of water, particularly those made of plaster or concrete. However, vinyl and fiberglass pool liners should never be pressure-washed because the jet can easily puncture or weaken these materials. Stick to manual scrubbing or consult a pool specialist for the best cleaning method if you’re unsure.

9. Some Outdoor Furniture

Although sturdy plastic, metal, or resin outdoor furniture is fine to pressure wash, pieces crafted from natural materials, such as wicker and teak, are much too delicate. The high pressure of the water can strip away their finishes, cause cracks, or weaken the joints. Instead, using a soft brush and mild soap is a safer option for cleaning these outdoor furniture pieces.

Note that you also want to avoid pressure washing outdoor cushions, pillows, umbrellas, and rugs. The water force can tear fabric, fray edges, and degrade protective coatings. Spot cleaning with gentle detergents or using a garden hose keeps these things clean and intact.