Pressure washing is a great way to remove tough stains and dirt. However, it can be dangerous if you don't know what you're doing or if you use the wrong equipment.
Here are some things that you should not use Pressure Washers to clean:
Wood and other natural materials
Wood is porous and will absorb water, which can cause it to warp or crack. Pressure washing also removes natural oils from the surface of wood, which can cause splintering and cracking over time. If you have a deck or other wooden structure that requires cleaning, you should use a manual brush and soft cloth instead of a pressure washer.
Marble and granites
These stones are extremely porous and contain microscopic holes that allow water to penetrate their surface. When you apply water pressure, the result is often a chalky white film that will eventually flake off entirely. This film can also create cracks in the stone's surface over time as it expands and contracts with temperature changes. Marble and granite should never be pressure washed! Instead, use a soft brush and mild soap to clean these surfaces without damaging them further.
You should never use a pressure washer on any electric panels, such as those that provide power for your home. Using this kind of equipment will cause short circuits and other electrical problems that could possibly result in an electrical fire or explosion. If you have any doubt about whether a particular surface might be an electric panel, then check with a professional before using your pressure washer on it.
Pressure washing is not safe on asphalt shingles because it can cause them to come off the roof and fall to the ground below. This is especially true if you are using a low-pressure nozzle or if the temperature outside is above 70 degrees F. If you want to clean asphalt shingles, use a broom instead of a pressure washer or hire someone who has experience with this type of job.
Pressure washers are powerful tools that can do some serious damage if they're used improperly. One of the worst things you should never use a pressure washer on is living things — especially plants and trees. The high-pressure water can easily kill them if used incorrectly or carelessly. It's also important not to use these machines near swimming pools because they can create suction in the pool liner causing it to burst open or even pull up loose deck boards from around pools!
The most important thing to consider when pressure washing your deck is how you're going to protect it. It's important not to pressure wash your deck before it's suitable, so it would be a good idea to dust the surface with a soft broom and give it time to dry first, this will also allow you to see damaged areas that will need work before using the pressure washer. The most dangerous part of using a pressure washer on wood is that there is no way for you to see what you are doing under pressure so any damage or marring that may have been done cannot be seen.