Pressure washing is massively expanding both as a solution to outdoor messes. Pressure washers are hardly new, but thanks to impressive social media pictures, the results are better known and celebrated than ever before. This has led to a lot of interest in how and why pressure washing is so effective.
You and many homeowners may want to know: How can something used to blast caked mud and gravel off heavy-duty vehicles also be safe to use on home siding, or soft roof shingles?
The answer is that pressure washers are highly-adjustable pieces of equipment. Safety and raw cleaning power can be balanced out across a wide range of surfaces—just enough power for a startlingly good cleaning, but not enough to damage. Here are some quick guidelines to the appropriate amount of pressure used for each of several common cleaning targets.
Vinyl siding cleaning can be delicate work. Special caution must be taken with the home exterior, because any bad spots will be easily visible to both homeowners and neighbors. To avoid any need for vinyl replacements, some of the lowest settings are used.
Some teams will use under 100 PSI, but that won’t necessarily be enough for heavily soiled homes in areas with exposure to high winds and heavy rains. The vinyl used for home siding should be more than sturdy enough to stand up to 500 PSI, and that pressure will mean a conveniently fast and effective cleaning.
Pressure recommendation: 100-500 PSI
A light touch is also required for roof cleaning, in fact lighter than most consumer-market equipment will allow for. Some professional teams switch to even lighter equipment, and use special settings and wands that allow for pressure to be distributed gently.
That the shingles are already bearing the weight of a person is very important to remember when choosing the right pressure. Also, the wrong pressure (and the wrong angle) can easily create lift under the shingles, knocking them loose.
The lowest possible settings are always used to start, but more pressure can be necessary if there is stubborn mold or mildew. However, low pressure is effective at removing growths even with only a few moments of exposure. Minimizing exposure to each shingle is an important part of a proper roof cleaning.
Pressure recommendation: <100-500 PSI
You can really let the pressure washer do its thing when you’re working with concrete! Concrete is perfectly safe under some of the highest pressures, and high pressure is often needed to get through years of dirt, debris and oil that has been cooked into the average driveway. Cleaning driveways can take a very long time, and it will take longer if the pressure isn’t high enough to make a difference from the beginning.
The starting pressure for concrete cleaning is usually 2500 PSI, and may be increased to 3000 as the cleaning is being done. When that’s combined with a flow rate of up to 4 gallons a minute (gpm), the power is more than enough to lift layers of gunk of a driveway in minutes flat. Cleaning with this much pressure can make an old concrete driveway look brand new.
Caution is still important, though. Holding the nozzle too close to the driveway when working with this much pressure can force the water into the tiny cracks between the mortar, causing it to lose integrity and form small potholes over time.
Pressure recommendation: 2500-3000 PSI
Wooden fences can be safely cleaned and completely rejuvenated with a pressure washer as long as the right precautions are taken. Even fences can be heavily soiled, especially if they haven’t been washed since they were first installed.
A light touch is sufficient for a lot of wood features around the home. 1000 PSI is a safe start for wooden fences, wooden decks, gazebos, patios and any wooden handrails. These same guidelines also apply to wooden siding. However, most woods can safely handle up to twice that much pressure if it’s necessary to remove the soiling.
Most professional pressure washers would not recommend exceeding 2000 PSI. At that level of pressure, even the hardest woods can begin splintering. Even at the lower pressure of 1000, it’s important to not allow the nozzle too close to the wood.
Pressure recommendation: 1000-2000 PSI
Brick walkways, siding and outdoor walls can all be very effectively cleaned with power washing. However, more care must be shown than is needed when dealing with concrete. Pressure cleaners must take particular care not to allow the nozzle too close to the porous lines of mortar between each brick.
The bricks themselves are about as resilient as concrete, but the mortar between them is far more fragile. You should start with about 1/6th of the pressure that you use for concrete at: 500 PSI. The pressure can be increased from there depending on how well the brick responds. The quality and resistance of brick mortar can greatly vary.
The damage to brickwork can appear almost immediately if excessive pressure is used. Deep scarring is easily possible if care isn’t shown when switching pressure or holding the nozzle aloft.
Pressure recommendation: 500-1000 PSI
Lawn Equipment & Trucks
Home lawn equipment and particularly soiled work vehicles can be pressure washed without danger. The main concern in cleaning either of these is the safety of the paint. Some of the widest nozzles are used for these jobs, so that there’s a gentler distribution even under higher pressure.
1000 PSI is usually a safe beginning point if the right nozzles are used. Special care must be taken to avoid touching anything that isn’t metal, or may be connected to the electrical system. For the safety of sensors and electrical components, professionals will not always agree to wash engine compartments.
Pressure recommendation: 1000-2000 PSI
We would love to talk to you about any other questions you have about pressure washing and power cleaning. Please contact us today with questions, or to schedule rejuvenation for your home.