Kristina McGuirk is a Milwaukee-based freelance writer and editor who covers kitchens, bathrooms, home improvement, decorating, and more for BHG.com. Previously, she worked for five Better Homes & Gardens special interest magazines over seven years. During her final year of undergraduate studies at Drake University, she began working on product-focused stories for titles including Renovation Style and Kitchen + Bath Makeovers and later added feature articles focusing on homeowner and designer stories to her workload. She joined the staff of Better Homes & Gardens special interest media as part of the kitchen and bath magazine portfolio, where she wrote, edited, and produced content around style, how-to, advice, and trends. She also coordinated budget-friendly kitchen and bath makeovers to be featured in the magazines, working with corporate sponsors and DIY homeowners to design hardworking and stylish updates to meet their needs. Bolstering her connections in the home design industry, she attended trade shows, product launches, press junkets, and manufacturing tours. She left the editorial staff for graduate school, and after earning her degrees and keeping with the industry, she's back to writing for the brand and covering a variety of home-related topics.

In addition to holding degrees in journalism and English, Kristina is an educated information professional with training in research practices and evaluating information sources. She looks for a variety of experiences to provide relatable, reliable, and diverse insight and advice in her writings.

A pressure washer turns the flow from a regular garden hose into a powerful spray. Whether prepping for a fresh coat of paint or simply washing away built-up dirt and grime, a pressure washer can be just the tool to tackle a variety of surfaces and projects around your home's exterior. But it can also easily cause surface damage if not used correctly, so preparation and restraint are key. Here's what you need to know to effectively and safely freshen up common exterior surfaces using a pressure washer.

Safety Note: Never power-wash a surface with lead paint. If it's possible the surface you're cleaning was painted before 1978, you should have it tested before beginning any work.

There are two types of pressure washers: gas and electric. They are rated for residential or commercial use, and the main characteristics for picking a model are the PSI (pounds per square inch) and GPM (gallons per minute). "The higher the PSI, the more power to blast the dirt from the surfaces, and the higher the GPM, the faster you can clean the large areas," explains Jay Sarkar, assistant marketing manager with RYOBI.

What you need depends on the project and surface you're tackling. More delicate surfaces require less pressure, and a simple rinse versus tackling stuck-on muck can also impact the oomph needed behind the spray. According to RYOBI, residential-rated gas machines with 2,600-3,400 PSI and 2.3-2.6 GPM are ideal for tackling a variety of larger home exterior projects.

Water pressure itself is not a cure-all; you risk damaging a surface by assuming a stronger force or lingering on one spot will remove stains, mildew, or gunk. "Soap can help to break things down better," says Sarkar. "For example, you would want to use an oil degreaser for stains on your driveway since just water by itself won't cut it."

Cleaning solutions can be applied with or without the pressure washer. Alternatives like spray guns, hose attachments, or a sponge or roller method can also get the job done, but pressure washers are especially helpful for something like siding, where added force moves soap into hard-to-reach places.

When applied with a pressure washer, detergent gets incorporated either through a soap tank on the machine or through a pressure washer siphon tube placed in an external cleaning solution. It's important to know what kind of solution you'll be using, and how it gets used with the machine. There are many pressure-washer-approved cleaning products specific to either the surface (such as concrete and driveway detergents) or the problem you're tackling (such as rust-fighting solutions.)

Start by relocating items like potted plants, patio furniture, and other accessories from the area that's to be cleaned. Sweep away large debris like rocks and twigs that could become projectiles when sprayed. Cover nearby plants and landscaping with a tarp, and be sure to cover outdoor lights, sound systems, or other features if they're in the direct path of water or could receive significant spray.

House and garage exteriors require additional consideration. Close windows and doors, and cover outlets, doorbells, light fixtures, and air conditioning units if possible. Shut off the electricity to exterior outlets on the section you're pressure washing. The goal is to not only avoid water getting inside your home, but also to prevent water and electricity from mixing.

If the area has any cracks or gaps, like missing mortar or dents in fencing, consider patching them before pressure washing. This will protect its structural integrity and prevent water from getting behind a protective exterior covering.

Follow the manufacturer's instructions for assembling the pressure washer. Attach any extension or telescoping wands you want to use; these are popular accessories for cleaning higher, harder-to-reach siding. For gas-powered models, be sure to add fuel and lubricant as directed.

Find a hose (ensure there are no leaks!) that will connect the pressure washer to your home's water supply. If using a cleaning solution, gather plenty of detergent and any related gear needed to apply it. Use safety eyewear and closed-toed shoes to protect yourself from splashback, ricocheting debris, or accidentally sweeping the powerful steam of water across your toes.

Having extra fuel and oil available for gas models can also save you from having to stop mid-project (and prevent damage to the machine).

Pressure washers come with multiple nozzles (though some machines have an adjustable nozzle with various spray settings), which control how the water comes out of the pressure washer. Nozzles are generally universal in color and degree, and machines might come with some or all of the ones listed here:

Nozzles with smaller degrees offer a stronger, more direct spray; larger degrees have a wider, less concentrated force that makes them safer to use on more surfaces. Home exterior projects will generally use a low-pressure detergent nozzle and a 25- or 40-degree spray.

While it is safe to pressure wash many surfaces, some materials, like fiber cement siding, are not typically recommended to be cleaned with a pressure washer. It's also wise to avoid pressure washing painted surfaces and fragile surfaces like old brick, wood, or stucco. Do some research on the material you intend to clean before getting started. Pressure washer user manuals usually have nozzle guidance, and when possible, consult the surface manufacturer information about the material. Always err on the side of caution.

Connect a regular garden hose to your home's water supply, and run it for 30-60 seconds to eliminate air and any trapped materials. Turn off the spigot, then connect the other end of the hose to the water intake on the pressure washer.

Consistent pressure from your home's water source is needed to keep the washer working smoothly. Use a water pressure gauge attached to the spigot to test your source's performance. If it measures between 40 and 60 PSI, the device should work fine.

If you aren't already, it's a good time to put on your safety gear. Next, put a low-pressure nozzle onto the end of the pressure washer wand; it should easily click into place. Turn on the water supply by fully opening the spigot. Aiming in a safe direction, release the pressure washer trigger lock and press the trigger to purge air from the setup, leaving it on until water comes out of the wand.

Now you are ready to turn on the pressure washer. For most electric models, it's as simple as an off-on switch, while gas-powered machines use a fuel valve, choke, and starter. But don't turn on the pressure washer until you're ready to get started; it's bad for the machine to run too long without being used.

Prepare and apply the cleaning solution according to the manufacturer's instructions. If using the pressure washer to apply the detergent, make sure you're incorporating it (into the machine tank or through the siphon tube) as directed, and that the low-pressure soap nozzle is in place.

For vertical surfaces like siding, fences, sloped driveways, or landscaping steps, apply the cleaning solution from bottom to top, sweeping from side to side so that soap runs downward and keeps the below areas wet. Manufacturer instructions will have advice on how long to let the detergent sit before washing.

Start with the lowest possible settings on the power washer. For most home exterior projects, this includes trying the 40-degree nozzle first.

Turn on the machine. Unlock and engage the trigger to activate the pressure washer, choosing a small area first to test the pressure. For something like siding, start with the nozzle at least four feet away from the surface, so as to not apply too much pressure right away. For decking or horizontal surfaces, aim the spray farther in front of you, not directly down. Walk closer and/or adjust the angle you're holding the wand until the surface gets clean but is not damaged. Do not get too close to the surface with the nozzle.

If the current setup isn't doing the trick, you can try switching nozzle, being cautious to start at a distance again. Nozzle tips should not be switched unless the engine is turned off, the pressure has been relieved from the wand, and the trigger lock is engaged.

Once you've found the right position, get cleaning. Spray away from yourself, especially with horizontal surfaces. For vertical surfaces, start at the top of the section you're working on, sweeping back and forth while moving down, so that dirt and debris fall into areas waiting to be cleaned. For even cleaning, use overlapping strokes and don't linger with direct pressure on one spot. Avoid directly spraying what you've covered up, like outlets and light fixtures, as well as areas that can let water into the home, such as doors and windows. Do not use the pressure washer around meters, satellites, cable boxes, power lines, or other utilities.

If you've split your project into sections, repeat the soaping and washing as necessary. Then, rinse away any residue with the lower pressure soap nozzle or even just a hose attached to your home's water supply.

When finished with the pressure washer, turn off the machine and engage the trigger safety lock. Next, turn off the water source. Undo the lock and engage the wand one last time to release any remaining water and pressure from the nozzle. Follow manufacturer instructions for storing the machine.

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