Pressure Washing: Can it get the job done?

Pressure Washing in Atlanta

pressure washing a concrete walkway using 25-degree (green) nozzle

A pressure washer makes quick—and satisfying—work of blasting away gunk. For cleaning walkways and stripping old paint from a deck, nothing compares to the unbridled power of these machines.

In fact, it’s easy to get carried away (or even inflict a serious injury—we’ll expound on that later).

Due to the universally satisfying ‘ooh and ahh’ when people see pressure washing works for the first time, many are led to believe it’s a better way to clean things. But, this might not always be a good idea.

In fact if you go at it just for the sake of seeing dirt get lifted off a surface, the supercharged stream of water can damage paint and nick or etch wood and even certain types of stone. You don’t want to be cleaning things so much that it destroys your property 

Below is a simple guide to knowing when it makes sense to clean with a pressure washer and when a garden hose and a scrub brush will suffice.

How to Determine Pressure Washer Strength

Not all pressure washers are made equal. As certain ‘pressure force’ is also delicately calibrated based on the surface of contact.

We measure how much pressure each model can produce, in pounds per square inch, giving a higher score to those with a higher psi. Then we fire up each pressure washer and use it to strip paint from painted plastic panels, timing how long it takes. Models with a higher pressure output tend to perform better on this test. 

We also measure noise, and you should know that almost all pressure washers are loud enough to require hearing protection. Finally, we size up ease of use by evaluating basics like the process of adding fuel and noting features that improve the experience. 

Regardless of performance, it’s standard policy to use only models that do not include a 0-degree nozzle, which we believe poses an unnecessary safety risk to users and bystanders

Read on to find out whether it makes sense to pressure-wash your deck, siding, roof, or driveway.

Deck: Yes, definitely.

Decks made from South American hardwoods such as Ipe, Camaru, and Tigerwood will hold up to the power just fine. Decks made of pressure-treated wood are generally okay, too, assuming you don’t hold the nozzle too close. 

Pressure-treated wood is typically southern yellow pine, which is pretty soft, so start with a low-pressure nozzle on an inconspicuous spot to make sure the spray is not etching or marking the wood. You’ll want to check your owner’s manual to see which nozzle and setting the manufacturer recommends for cleaning decking, and how far away from the surface you need to keep the nozzle. In any case, work along the length of the board, going with the grain of the wood.

Not all decks need to be cleaned with a pressure washer. Newer composite decks from brands such as TimberTech and Trex often resist deep staining in the first place and can be cleaned with a light scrubbing. If a light scrub and rinse with a garden hose isn’t enough to get your composite deck clean, check the terms of the warranty before using a pressure washer to make sure you don’t void it.

Roof: Definitely, No

Tempting as it might be to blast away unsightly moss and algae, using a pressure washer to clean your roof is dangerous, not to mention potentially damaging. 

For starters, we never recommend using a pressure washer while you’re perched on a ladder because blowback could throw you off balance. The powerful stream of water can also loosen roof shingles and, with asphalt shingles, strip them of the embedded granules that help extend the life of your roof.

Instead, spray down the roof with a cleaner that kills mold and moss or apply a 50-50 mixture of bleach and water in a pump sprayer and let the moss die on its own. Make sure to build up pressure in your pump sprayer from the safety of solid ground before climbing a ladder to spray your roof.

A longer-term strategy, if there’s an excessive amount of shade, is to trim overhanging branches or cut down trees to allow sunlight to hit the roof. That’s the key to preventing moss from growing in the first place. 

Concrete Walkways and Driveways: Yes you can

Concrete can readily withstand a powerful cleaning without much concern over etching. Generally, a finer nozzle will prove to be more effective at spot-cleaning grease stains. For moldy or mildew-covered cement, use lower pressure and coat the surface in suds first. High powerful pressure washers, would serve you well for this task, but it includes a 0-degree tip, which we advise discarding simply because of the health hazard it envokes.

Sidings, Yes and No, it depends

Vinyl siding is pliable and can typically withstand pressure washing without much concern. The same goes for fiber cement siding. Aluminum siding, however, can dent, so it’s best to start on the lowest pressure setting with a broad nozzle, and use more concentrated blasts only for problem spots. It is recommended to use a model that’s particularly easy to handle and maneuver, which is nice when you’re working your way around an entire house. 

Wood clapboard siding can be effectively washed, too, but if your house was built before 1978, have the exterior paint tested first by an EPA-licensed lead-remediation specialist. If you knock old lead paint loose, it will settle in your soil and never break down because lead is a heavy metal.

A word of caution: When using a pressure washer to clean any siding, you need to prevent water from becoming trapped between the siding and your home’s sheathing, because the moisture promotes mold. Repair or replace loose, damaged, or missing siding, and take special care not to spray water directly into any gaps around doors, windows, or under the lap joints on siding runs. 

Don’t pressure-wash shingle siding—the pressure can knock the shingles loose. 

Responsible Pressure Washing Guidelines

Pressure washers come with nozzles ranging from 0 degrees to about 40 degrees. The higher the number, the wider the spray pattern and the less concentrated (and potentially dangerous) the stream of water. Consumer Reports recommends against using a 0-degree nozzle at all because it poses an unnecessary safety risk. Water concentrated to such a fine point can pierce many surfaces, including protective boots.

If your pressure washer came with a red 0-degree nozzle, toss this nozzle out. The next size, a 15-degree nozzle, will do just fine for detail work, such as removing moss from the grooves between pavers. And always wear hearing protection, protective footwear, and gloves while you work.

Have a safe and product pressure washing ahead! Or you can let the pros do the pressure washing for you. Contact us today to see our time-saving offers.

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