4 Reasons You Should Never Pressure Wash Your House

By Scott Sidler • August 31, 2015

never pressure wash your houseEverybody pressure washes their house. But few people know that the way it’s usually done is NOT good for your house.

You may just be going with the crowd, but in this case, the crowd is wrong, and you’re likely causing big damage that you have no idea about.

Pressure washing is usually the first step in getting a new paint job, so I see a lot of painters doing it and doing it wrong.

It’s not just unknowing homeowners doing this, it’s the professionals as well! Painters and pressure washing companies walk away from a house with a clean exterior, but the work they did has caused untold damage inside the walls of the house and other places.

There are four main reasons you should never pressure wash your house. Four ways that pressure washing does more harm than good. At the end, I’ll discuss the right way to way wash the outside of your house, but first the bad way.

 

Reasons to NOT Pressure Wash

 

#1 Water in the Walls

To me, this is the worst kind of damage you can do with a high pressure washer to a house. Commercial pressure washers shoot water at pressures starting at 1500 psi which isn’t too destructive, but they can go upwards of 3300 psi, which will blast through solid wood, asphalt, and even concrete (I’ve done it) if they’re close enough.

If you have a wood frame house with any kind of wood siding (clapboards, shiplap, board and batten, shingles, etc.) there is an excellent chance that washing your house with a high pressure washer will shoot water up under the siding, potentially soaking wall cavities, insulation, wiring, flooring, plaster, etc. Nothing is beyond the reach of these powerful water guns.

[Tweet “Your house is full of gaps and cracks and high pressure water will always find its way in.”]

Once the water is in the wall, it is often difficult for it to evaporate. Often, in the painting process, a house is pressure washed, then caulked and patched and finally painted. Essentially, the painter is soaking the inside of the walls and then sealing the water in with a fresh coat of caulk and paint.

I have seen moldy insulation, crumbling plaster, and cupped flooring all from a pressure washer’s work. Nothing in your walls likes to be wet so keep it dry.

#2 Missing Mortar

A lot of people think that since they have a brick house, they are safe to pressure wash. Think again! Old brick and mortar are softer than the new stuff today and can be easily blasted away with high pressure water.

I’ve seen brick houses with the mortar almost completely blasted away by pressure washing. And the expense of repointing a brick house is probably 10 times what the pressure washer charged you to wash your house.

 

#3 Gouged Wood

When pressure washing, a lot of painters will get right up close to the surface to try to blast loose paint off. They often succeed and then that 3000 psi water is blasting right into bare wood. It digs holes in the surface and furs the wood grain up damaging the siding.

Unless you’re into carving your name into the side of your house with water, this is yet another reason not to pressure wash.

#4 Lead Paint

It’s always there lurking beneath the surface on an old house. We all want it gone, but removing paint with high pressure water is not the solution.

It causes lead paint chips both small and large to be blasted all around the yard and get mixed into the soil where the kids can potential ingest it.

If you don’t have kids, think about the neighbors or the next folks. Lead paint is everyone’s responsibility. Read more about lead paint safety here.

 

 

When You Should Pressure Wash

Don’t think that I am against pressure washers. They are a great tool, I just see them being misused way too often. There are times and projects where a pressure washer is the best tool for the job and I want to be sure to mention those as well.

Some projects work best with high pressure (2000-3000 psi) and others with lower pressure (1250-2000 psi)

  • Decks (Low pressure)
  • Railings (Low pressure)
  • Wood Fences (Medium pressure)
  • Vinyl Fences (Medium pressure
  • Asphalt (Medium pressure)
  • Concrete Driveways & Sidewalks (High pressure)
  • Metal Patio Furniture (High pressure)
  • Stone and Pavers (High pressure)

So, if pressure washing is dangerous for your house what can you do to get things clean?

 

The Low Pressure Option

I’ve found that using a homeowner grade pressure washer allows me to safely wash a house with the pressure low enough to be relatively safe and I’ve outlined my methods in an earlier post Pressure Washing an Old House.

Ultimately, the safest way to clean and prep the exterior of your old home (especially wood houses) is to use a regular garden hose and spray nozzle along with an extension pole with a nylon scrub brush.

It takes longer, yes, but it actually does a better job at cleaning the house and preparing for paint in addition to being a hundred times safer for your house.

I’m not sure how many of you will follow this advice, but I would be remiss to not tell you the dangers. What you decide to do with the information is up to you!

 

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139 thoughts on “4 Reasons You Should Never Pressure Wash Your House”

  1. I live in an Orwellian Big Brother HOA subdivision where neighbors literally walk around and take notes of everything wrong with the houses and yards. One man is complaining because people don’t pressure wash their houses, so now I’m freaking out. I was researching when I came upon this information. Now I’m even more confused than ever. I want my house to look good, but I don’t want to damage it. I have a horribly white house (love the house, hate the color) and I’m not even sure what siding it is. My husband is disabled, so I’m not comfortable with many DIY options. This makes me not want to pressure wash, but I live with the constant stress that my house/yard won’t be perfect enough for the analy retentive HOA board.

  2. I’m a professional paint contractor and have been in business 26 years, specializing in both exterior and interior painting. I’m sorry but I’m going to disagree with you. If you want to extend the life of your paint you need to pressure wash at least every two years. Mildew is attracted to dirt, dust, pollen and any other atmospheric contaminants that are on your homes substrate. These contaminants serve as a food source for mildew and once the mildew has eaten through the contaminants, it starts to eat your painted surfaces. Shooting water in to interior walls is false. If you know what you are doing, or you hire a professional, you don’t have to worry about this. Damaging mortar? No, not unless the mortar is in terrible shape already and if it is, you need to have your brick repointed. Light pressure is fine for some areas but if it’s a two and three story house, light pressure will not do a thing to remove dirt and debris. A clean house is generally a well maintained house.

  3. Looking to buy a 1912 historical home and it needs cleaning on the outside. I had a feeling that having it pressure washed would be damaging. Your article confirmed that. Thanks for the advice!

  4. Softwash is the way to go, don’t waste time with a brush or long pole and certainly DO NOT POWERWASH your home or roof.
    Softwash is a technique that uses biodegradable detergents to kill the organisms (mold, algae, mildew) that grown on your siding and or roof, and the stains they leave behind. When you pressure wash not only are you causing potential damage and voiding warranties, but you are only washing away the vegetation of these organisms. Soft washing kills said organisms and will leave your house actually clean, and lasts much longer than powerwashing.

  5. In my experience, paint peels off BECAUSE OF WATER. Bottom shingles lose their paint first. The bottom of brick moulding around doors loses its paint first. The bottom of brick molding around windows (where it meets the sill) loses its paint first. Wood comes from trees which use capillaries to carry water up to the leaves. This is a physical process that still goes on, even when the tress are cut up tp make lumber. Any joint (scarf or butt) between two boards will often lose paint. Inside corners lose paint faster than outside corners. Have you ever seen skirt boards at the bottom siding panels that someone added to hide water damage to the siding? You get the idea. Pressure washing is a terrible idea if you brush or roll. Rolling or brushing will mix any trivial amount of dirt into the paint where it won’t matter. What the heck, most paint starts out as white paint, the white color comes from titanium dioxide which is a mineral which comes out of the ground (like dirt). If you have a really dirty house and you are going to spray paint (especially on a hot windy day) then it would be a good idea to clean the surface somehow, but in a simple way, from the top down. I have never seen anyone pressure wash a house from the top down. They stand below and shoot the water up. Wrong. Shingles, lap siding, drip caps, everything is meant to shed water from the top down. For houses that have Masonite siding, don’t use water, in any direction. That siding was so poor there was a class action lawsuit. For most siding, sweep the surface with brushes to get rid of loose dirt and cobwebs. Get rid of splashed on dirt from the close-to-ground areas with a hose and brush (but no water on Masonite ever).

  6. I can’t tell you how many of my neighbors have their cedar shingle siding power-washed. My painter husband warned against this numerous times to homeowners who insisted on power-washing, and he walked away from those jobs. Lots of painting contractors out there will tell customers what they want to hear, and blast away, destroying the integrity of the wood grain and essentially injecting moisture into the shingles and surrounding infrastructure. Then they seal all that moisture in with chalk and stain or paint.

    I just had my 100 yr-old house re-shingled with white cedar that was pre-stained (double-dipped). It was expensive, to be sure. If mildew becomes a problem the manufacturer recommends gentle washing, basically with a hose, a soft brush, and soap and water.

    Buyer Beware: Power-washing wood shingles will look good for just a few years, only to have to be repeated at great cost. And there is a good chance that the contractor won’t still be in business when the same problems arise.

  7. Our house is vinyl sided and has dirt on the siding and some green mold. Is it safe to have some one power wash the house with what he called “soft wash” not high pressure?

  8. It’s also incredibly easy to shatter a window and shred window and patio door screens with a pressure washer. The money spent on a professional power washing company is well worth avoiding that costly damage.

  9. if I powerwash the house myself with hose, is there a product you recommend that can block algee and mold from building up?
    thanks!

  10. We bought a cottafe in a lake in Maine all redone inside. The house has cedar shingles exterior all sides peeling to the degree that I can get some shingles almost clean by simply running my glove across it. Other shingles are solid paint. I’ve power washed and scraped. Neighbors were surprised at how fast it peeled and wondered what my predecessor used or did wrong. We intended to stain but not being able to get all the paint off leaves me wondering what to do. Some neighbors said it was the thpe lf shingle that never dries. I am not looking to reshine if not necessary. Ideas?

  11. Thank you for the info…I will surely ck into this before letting anyone do the washing…It makes perfect sense to me…

  12. OK, I apparently made a mistake and hired a painting company to paint my house. It didn’t seem funny at the time that pressure washing was included in the job. I told them to use low pressure on my siding (Hardieplank) so as not to damage the siding and I also told them not to shoot up in the vertical direction to avoid water in the walls, It looks like a saw the problems you are mentioning here.

    So with this work being done in early January, and the paint to be applied four months later in May, have I lost any or all of the benefits from the power wash?

    1. I’ve been a professional painter for 42 years on my own business what you’re talking about power washing that there’s reasons why you shouldn’t do it weathers reasons why you should and just sit there and say that the painter hey if you’re a good painter and you know what you’re doing proceed if you’re some dumb kid who don’t know what he’s doing that’s a different story back to sit there and tell people not to let somebody power wash the outside of their house well I’ve never gotten water inside somebody’s walls I’ve never tore up somebody’s would by grinding into it with tip that will do major damage you’re sitting here telling all these people on here something you think but it’s not true

      1. Yes, this article s very wrong. If you know what you are doing, it is not going to harm your house by pressure washing. Most professional pressure companies like mine are moving to a technique called soft washing. Very safe and does a great job. Whoever who wrote the article apparently does not do this for living and only wrote about the mistakes that uninformed do! Get you a professional and experienced pressure washer.

  13. The fact that many paint companies instruct home owners to pressure wash gives me reason to believe you are an alarmist. These large paint companies can be liable for any incorrect tutorial on home prep,
    I am sticking with the paint companies recommendations. When done properly, power washing is the best method for exterior preparation.
    Just ask Bob Villa from this old house or Sherwin Williams.

    1. Amen I’ll back you up 100% people put on hear anything they want to and some people believe everything somebody says on here this is so untrue what this guy just got through saying about not power washing the outside of a house before you paint so what he’s saying is you should paint dirt

    2. I’m not sure we read the same article. It didn’t seem like he was trying to alarm anyone, just caution that it’s something not to take lightly and make sure you do or have done correctly.

      1. I agree. He wants homeowners to know it needs to be done right, or damage could be done that you won’t know about for years down the line.

  14. I have wood home with fake brick on the outside and where the down spouts are is very dirty, I would like to clean my home and have it sealed so I don’t have this problem anymore what do you recommend

  15. Soft wash systems are safe for just about every surface and designed to effectively dissolve thick dirt and grime on outside walls, roofs, and concrete, so you can then use low pressure to rinse it all away. They’re a perfect option for older brick and asphalt shingle as well as aged and brittle windows, wood decks, and patio pavers. Thanks for the tips!

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