How to Pressure Wash a House

As the owner of Neptune Clean, and highly trained Jedi-Washer, I often hear homeowner confessions of failed DIY home cleaning attempts. The conversation always begins with “I have my own pressure washer but…” followed by the problem they encountered.

I always encourage homeowners to save money where they can. Heck I’m an avid DIY’er so I can’t blame them for wanting to take care of a simple exterior house cleaning project.

One common mistake homeowners make is using too much pressure to wash their siding to remove organic contaminants like mold, mildew, and algae. Using “high pressure” can damage siding. It can also force water under vinyl siding, into soffits, or under door and window jams.

Brick is more forgiving of course but wood siding like cedar is more fragile than vinyl. What homeowners don’t realize is that professionals rely on cleaners and each of these siding types require a different type of cleaner.

before mailbox clean
Soft Wash Docks Piers

Here’s my first pressure washing tip:

Professionals use a “soft wash” method to apply a cleaning agent. The most common cleaner is a diluted blend of sodium hypochlorite (bleach) and surfactant detergents.

 The mild soap is applied with a low-pressure spray to all the surfaces of your siding. The soap does the work (not the pressure washer) and removes the organic material. All you must do after a short dwell time is give your home a good rinse.

 Here’s my second pressure washing tip:

Hydrate all the plants and grass around your home to protect them from the cleaning agent. A thin coat of water fills the cells on the surface of leaves reducing exposure to the cleaner. If left unprotected, direct exposure to cleaning agents may burn leaves and grasses.

 Here’s my third pressure washing tip:

Before cleaning your home, cover anything you don’t want exposed to the cleaning agents like copper light fixtures, door handles or exotic wood doors. Sodium Hypochlorite will accelerate rust on iron or the patina on copper. Also tape electrical outlets where they meet the siding to reduce the chance of tripping a GFCI circuit breaker.

Here’s how to safely clean home siding yourself:

Most homeowner level pressure washers have a downstream attachment that allow you to “softwash” your home. You can purchase house siding cleaners from the big box home stores. They sell it by the gallon, and it works well with the downstream feature of your pressure washer.

Here’s my fourth pressure washing tip:

Your downstream attachment uses a venturi effect to draw cleaners into the flow of water going to your hose and nozzle. It’s typically at a 4-1 ratio. That’s 4 gallons of water to 1 gallon of cleaner it draws.

So, if the cleaner you purchase recommends diluting your cleaner 4-1, you simply drop the downstream pickup tube from your pressure washer into the cleaner and you’ve got a 4-1 ratio you’re spraying on your home.

 To begin pulling soap through your pressure washer, all you do is change the pressure washer’s nozzle to the black “soap” tip. Next, drop the downstream hose into your soap mix and begin applying the cleaner to your home using your pressure washer. The soap may take a minute to travel the length of hose you’re using so be patient.

Let the mix dwell for 20-30 minutes and then rinse it clean. Of course, that is if you have a single-story home. This is a pressure washer capability problem. Many consumer level pressure washers don’t have enough power to reach the second story gable ends. You may have to purchase a professional soap shooter tip to reach these heights.

 Another common problem I encounter is customers using high-pressure to clean their wood decks.

 Here’s my fifth pressure washing tip:

Never use high-pressure on your wood decks or fences. Many consumer level pressure washers can produce up to 3000 PSI or pounds per square inch of pressure. This is not only dangerous to a person but can rip into the wood’s fiber shortening its life.

 Professionals always use cleaners to do the heavy lifting for them. I use oxygenated cleaners and surfactant mix on wood. It’s works great to remove mold, mildew, and algae growth.

 You may have read that Sodium Hypochlorite also works on to clean wood. This is true, it does remove mold, mildew, and algae but there’s a downside. Deck cleaners containing bleach harm the woods lignin which is the organic substance that binds the cells, fibers, and vessels of the wood.

 Pressure washing Professional always use a two-step process when cleaning wood. After rinsing the wood surface clean, apply a wood brightener to restore the wood back to it’s natural color.

 Here’s how you can do it yourself:

Applying wood restoration cleaners is a little different than washing your home. All you need is a quality pump-up sprayer. Follow the directions on the wood cleaner you purchase for the correct dilution mix and application methods. WARNING: Oxygenated cleaners will produce oxygen increasing the pressure in your sprayer so purchase one with a pressure relieve valve.

 Add the cleaner to the pump-up sprayer and pump it up. Spray the entire wood surface and let dwell as directed by the cleaning agent’s directions.

 After the oxygenated cleaners have done their work, you can rinse the surface with a pressure washer using a low-pressure tip or simply increasing the distance between the nozzle and the surface you’re rinsing.

 Applying a wood brightener is usually done exactly like the cleaner but read the directions on the product you purchase to make sure. Lastly, admire the new beauty you’ve uncovered through all your hard work

 Bill Seith

Owner of Neptune Clean LLC