Everybody 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!
Founder & Editor-in-Chief
I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.
Had my home pressure washed last week and now the basement is randomly taking in water. Plumbing company came out and said there is no leak. Any suggestions or advice?
My exterminator just came to my house for a springtail infestation (tiny bugs that jump and like moisture). I live in Michigan and my roof/shingles are covered with moss and algae. It is growing up the side of my brick home above parts of the roof. She suggested getting the entire exterior of my house and roof power washed to get rid of moss, mold, algae etc. What are your thoughts on this? If you don’t think a low pressure wash is a good idea, do you have any suggestions?
Thx!
Low pressure (under 1200 psi) should be just fine with a brick building.
As a pro pressure washer, I find your article refreshing. Power today can equal pain (in your pocket) tomorrow.
Thanks William!
We live by an airport and have black grime on white plastic window frames. I believe the black grime is jet fuel among dirt and other things. If I wanted to pressure wash these window frames, what psi would you recommend?
Under 1000 psi is the safest way.
I’m getting ready to hand wash and hand paint my two story wood siding house. I may spray the primer on but everything else will be done by hand. I am getting a lot of pressure to use a pressure washer but I’m not budging. It’s an especially bad idea here in Alaska. I’m not wasting the premium paint I bought by bad prep work.
Scott,
I now need to clean the bricks on my Mom’s house — the lower ones on the sides of her house that have no gutters. The house is brick & mortar and was built in 1957. There are some new, small cracks in mortar from all the earthquakes Okla has experienced the past few years. Again, power washing has been suggested, but after the bad experience on my house (see my response to Mano), I am resisting my siblings’ insistence. Even if I have to do it alone, I’m going to use only a garden hose rather than a pressure washer.
MY QUESTION: What product(s) should I use? What soap or cleanser? Do I scrub or just leave on awhile and rinse off with a good jet of water? Specifics please — name brands, etc. THANKS!
Hi I’m selling my house and it has wood siding which totally needs cleaning. Don’t want to re-paint, just want it to look presentable and clean for when the buyers come to preview. What do you suggest?
I really would like to know of one example of pressure washing causing mold damage. The little bit of water that will make it thru the cracks will surely evaporate over time. Mold needs a constant supply of water over time to start working its way. Plus, there is nothing air tight when you paint over a wall since what’s behind the paint is stucco mix crete, and chicken wire. I would
have to see it to believe it.
I see people use pressure washing as their prep for paint. So when you blast water into the walls then seal up the exterior with caulk and paint the next day that’s a recipe for disaster.
To Mano, HERE IS AN EXAMPLE OF PRESSURE WASHING CAUSING MOLD.
We added vinyl siding to cover the old wood siding on our home. We added good, thick panels of insulation under the siding. 3 years later, the north and east side of our house was covered in spots of mold or mildew — it was awful and got worse.
——-Our house is 1943 lath & plaster. The siding is good quality and has weep holes. We added extra attic vents to the soffit and added another whirly-gig vent to the roof. There should be no problems with mold — but after pressure washing the siding – the mold move inside! — We live in Okla where the humidity is NOT as bad as it is in Houston or New Orleans! And we have lots and lots of wind to dry things out. We even had a drought —- but the spots got worse.
Four years after adding the siding, we were talked into having the north & east OUTSIDE vinyl siding pressured washed to remove the mold/mildew. Within 5 months of the pressure wash — dark spots appeared on the INSIDE north wall of the house and grew and caused the interior wall paint to blister and fall off. Of course, the dark spots were mold or mildew or both. I didn’t bother to have it tested. I just used diluted bleach several times to be sure it was gone and then put 1,000 coats of sealer/primer that had a mold deterrent in it on the entire interior north wall before repainting.
——-We have lived in this house for 25 years and the ONLY thing that had changed was having it pressure washed. This INTERIOR mold problem did not appear during the 4 years after having the siding added — it appeared within 5 MONTHS after pressure washing the outside! ———- If I’d known that the siding was going to have to be HAND WASHED every 3 years or so, I would not have added siding. I would have just repainted — which has to be re-done only every 5 to 8 or more years depending on the quality of the paint.
Also, the guy who did the pressure washing is a professional and, before painting our detached garage to which we had NOT added siding–he pressure washed it to remove peeling paint – instead of hand scraping & sanding. He did what Scott mentioned — he got too close with too much pressure and cause some of the wood to fur badly.
A year later, when I was repainting to fix his crappy work, I had to drag out the sander, then prime the now bare spots and then paint – 2 top coats — as it should have been done to begin with. The ‘professional’ used Behr paint & primer in one — it sucks. I’d like to used the pressure washer on the ‘professional’ who caused so many additional problems!
Im looking into staring at power washing buisness im new to the field and would like some tips, what type of pressure washer should I get? Gas or electric? How much p.s.i , what are things I should be aware of when starting good a pressure washing buisness such as is their any laws on the water use? Pls help
DON’T start a pressure washing business. Read this article about how harmful it is.
I have a Spanish style plastered house which really needs pressure cleaning before painting, but we have severe water restrictions prohibiting the use of municipal water. There are many layers of paint needing removal, as the surface is chalky from paint failure. Are there any suggestions on how to clean the exterior walls?
We usually clean with a wet scrub on a firm bristle brush then, scrape and sand any failing paint. Even with a water restriction you still have to wash the dirt and debris from the building before painting or the paint will not adhere.
While pressure washing is a great tool to clean many surfaces; you are correct about houses. You need to adjust as a homeowner on how you want to go about cleaning the surfaces of the house. A big thing that I have witnessed some homeowners doing is pressure washing their house and have some made the mistake of washing the roof at the expense of the destruction of the shingles on the roofs. I love your tips on different pressure levels for specific surrounding areas of the house and I would have to agree of this garden hose being the primary tool for the cleaning of the walls of the residents house. Great and educational article.
I moved into a red brick Victorian home built circa 1880. The cream coloured accent bricks on the house, above windows and doors and stone window sills have been painted over with white paint. Can I pressure wash the accent bricks to remove the white paint or should I consider a gentler method like soda blasting?
I would use a paint stripper like PeelAway 1 to get the paint off safely. Power washing could create some additional issues and likely won’t remove all the paint.
May I suggest foam and scrub vinyl-siding instead of pressure washing that leads to mold an rot. http://www.carolinawooddecks.com/Vinyl-Siding—Shutters.html
Great article, really appreciate the post. I just bought a 90 year old home and am about to power wash. Quick question for you: our covered side porch has cobwebs and dirt. We have old columns with nice woodwork at the top that attracted lots of the grime. Should we be okay to use a power washer on a lower spray in the area, including spraying at an upward angle? The bottom side of the roof is also all wood and filthy. Want to house the whole thing down. Any thoughts? Thanks for your time , Scott!
Greg
Greg, you can certainly use a pressure washer at a distance to resolve those issues. Try keeping the pressure at no more than 1500 psi and keep the tip at least 3-4 feet from the surface. That should clean off the dirt and cobwebs but not force water into places it doesn’t belong.
You need a low pressure soft wash using bleach it will eat all the cobwebs and black mold. Just using water won’t work.
As a pro pressure washer, I find your article refreshing. Power today can equal pain (in your pocket) tomorrow. No short cuts folks. I see lots of people who don’t get this. Treat your home with respect and a little TLC and it will treat you back well.
Just added brick pavers, new step & retaining wall plus landscaping walls to my home. Caused a lot of dust. Paid 900.00 to lightly pressure wash my tile roof and house being that it is only 4 yrs old. I am now left with some white residue all almost on my whole house! Especially the front porch and the pavers are a complete mess! I paid 14k for the pavers and now they look old and gross!
Can you tell me how to fix this? I am in shock……………….
Thank you.
The sad thing is, most people get caught up in thinking that more PSI=clean. Your cleaning agent will dislodge the dirt. As for staining, there are options for that, and high pressure isn’t one of them. With the right cleaning agents, you can apply the soap, let it sit, then rinse with a water hose; letting the soap do its job.
High PSI destroys what most are trying to clean. The correct cleaners and low psi or soft washing with a little elbow grease is the answer. TLC and work always works better. I worked for a company as a regional field manager and I have seen first hand what psi and lack of experience will do and it can cost thousands to fix. I no longer work for that company because they considered themselves professionals and were making hundreds of thousands of $ destroying properties and always had fine print contracts to weasel out of responsibilities. I now have my own company and we never PSI wash homes , we soft wash and use soft brushes with eco friendly cleaners. Investigate, read and then use elbow grease , you will enjoy the outcome !
cool information …thanx for share with us…
So do you think you should literally never pressure wash your house? Or are there certain circumstances when you should?
After my experience, NO! I am left with a super mess!
If its dirty pressure wash it! Soft wash. Bleach does all the work. No high pressure and it will be all good!
I remember long ago my grandpa wanted to clean his tiled porch. He did. It came out clean but half the grout came out too! Yeah, that wasn’t a good idea!