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.
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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.
Hello. Help! How long after pressure washing should you paint your house? We pressure wash our house and on the sun facing side now it’s uneven looking. I think it needs to be repainted on that side. Unless you have another suggestion?
At least a week to ensure everything has dried out. Use a moisture meter on the wood to be sure.
Hello,
Could you please help me with some info.
I am interested in start up a small business washing fasades and stone in my town. I would like to ask you which power water pressure is required, is it ok around 200 bars? or 250 is needed? Also what is better for work electric one as Karcher Profesional HD 10/23 4 , or benzin models? What is the best option for the start? Thank you in advance!
Electric ones are useless for a business
4000 PSI 4 gallons a minute Honda is commercial grade.
Starting a business and you dont even know what pressures or quality of machines you should be using?! Wow, I hope you have good insurance!
I am glad that you pointed out that it is not a great idea to use a pressure washer to clean brick sections of your home. That is good for me to know because a section of my home is brick and I have been wanting to clean the siding part of my home recently. I will have to make sure that the pressurized water doesn’t hit the brick. http://www.ablasttothepast.com/residential
I have synthetic stucco (EIFS or Dryvit) 25-years old that needs cleaning. Suggestions pretty please!
Soft wash
I think the title of your article is your perception and misleading. I could point out a dozen issues with your statement. There are so many variables with power washing as you misapropriately listed above.
I will offer you a challenge instead of insulting a profession try to bring a positive article.
Agreed!
Soft Wash. “pressure washing”. Doesn’t matter what the situation is, algae, mold, mildew, paint preparation. Use the correct chemicals for the job. Add rubbing alcohol to your mixes to evaporate anything you think would be left behind. I have mixes for everything including snow removal, it also helps in prevention of snow to stick to any surface. 1 quart water, 3 drops of dish soap, and 1 ounce of rubbing alcohol. Simply stating use the correct mix for what ever job you need accomplished. I absolutely agree with the siding cleaning. There are correct ways to pressure wash siding at 4,000 PSI, but there are correct ways of cleaning siding at 40 PSI. Depends on the amount of money you have and obviously time. If you are pressure washing at 4,000 PSI you must have absolute attention at all times, follow the lay overs of the siding. Use your mix from bottom to top so it does not leaves drip stains. And fully rinse. As for the 40 PSI machines, I normally use an algaecide or concentrated bleach. Some key things you want to do prior to using this is severely water down and plants and grass in surrounding areas, this will allow the bleach/algaecide to not stick to the plants or harm them. Ensure you wash in a downward angle for high and low pressure washing. And finally allow the bleach/algaecide to do its job for about 10 minutes before rinsing it off. They are really not hard concepts, all achieve roughly the same cleanliness, I’m going to be completely honest even soft washing with hot water will not remove everything. You need a heavier PSI to get all of the mold/mildew/algae off. And if you’re not getting everything off I honestly see no good in washing at all as it will grow right back. Just some basics to follow so you don’t have to hire a professional. For my business I personally soft wash everything first, however when everything doesn’t come off the roof, or sides no matter what type of siding you have, it still needs to be removed. Hand scrubbing is very good where you can reach it, but doing so on a heavily pitched roof is absolutely unsafe and absurd. Grab the extension pole and 5 minutes later everything is clean.
Do you have an suggestion for uneven appearance after pressure washing on side of house that gets the most sun.
Is the siding vinyl?
Hello Anne,
Is the house wood or vinyl?
I believe you’re probably referring to vinyl siding which can be Common on the “sunny side” of a house.
Much of the uneven look is Due to the vinyl fading over time as a result of the Sun and elements. In addition, Vinyl doesn’t always fade evenly. Also, the areas where there was “dirt”, “oils”, somewhat, “shaded” those areas if the vinyl.
Lastly, the uneven look is Sometimes caused by improper pressure washing.
I would reccomend matching a paint color and painting it IF you don’t mind the future maintenance & upkeep. Hope this helps!
Help! A company just pressure washed my house and i think they painted too soon (about a day later). Two days after the job, my home now smells like mildew/mold! What should I do? Is this dangerous for my health?
Yes that is too soon. Try running some dehumidifiers in the house and setting out some packages of damp rid. The smell will go away and the moisture eventually drop but with the house now sealed up on the outside with paint it has no where to evaporate but indoors.
You might try this Living Streams Mold Relief probiotic that you apply inside with a fogger machine. Wayne Blakely spoke about it recently: https://oneradionetwork.com/?s=blakely
We have recently purchased a beautiful property with a cedar cider sided cottage. The siding is in excellent structural shape (about 6 years old) but has never been stained or otherwise treated. It’s darker than we prefer and I thinking of low-pressure washing it, then using a transparent stain. Any thoughts?
Low pressure would be ok but hose sprayer and scrub brush is always better.
Ok got it. Thanks for letting us know. Great! I think 1250-1500 psi would be best for cleaning wall. If you suggest the best one that will be great!
We have an old house with asbestos siding that is in good condition. We are getting ready to have the trim work around windows painted. The house needs to be cleaned outside, though. I am reluctant to have someone power wash it because I don’t want the paint flaking off the siding. My biggest concern is under the eaves where it really needs to be cleaned. There is mesh wire that opens into the attic to keep the attic cool and I don’t want water getting into the attic. My question is: 1) should I skip the power washing and just use hose and 2) how to keep the water from going into the attic because under the eaves is where I really need to get clean! Any help would be appreciated!
Sandy, I would use a hose and scrub brush. And to keep the water out of the attic which a pressure washer will definitely do. Cover up those openings with plastic during washing.
Thank you for the information, Scott. I had that dreaded feeling the more I thought about it that power washing was not the way to go….I don’t think it will hard at all to wash with the hose and scrub brush. I have a helper so I think between the two of us, we’ll be able to do a good job….then on to the cleaning windows and painting! This old house is going to look really good………and I’ll be following your blog for ideas!
Awesome!
What about a mobile home that has green stuff on it, being on the shady side of the house? Should it be low or medium pressure? Also if I do it with a hose what cleaning products would be recommended?
Low pressure is always best or a hose with a scrub brush. Try using Jomax cleaner to remove mildew and algae.
I just got a pressure washer so that I could clean my house with it. However, I really appreciate your point about how it can get under the siding and cause more damage. I definitely don’t want to do anything to ruin my house, and so I think that I will just use a mop on the parts that I can reach or hire a professional. http://sidepro.com/improve-propertys-value-siding-replacement-seattle-wa/
Please help…my husband and I are rehabbing an old completely cinder block home. He wants to pressure wash the inside walls before we frame for sheetrock. I’m nervous that it may cause more damage than good. Is it safe to use a homeowner grade washer?
If it’s completely cinderblock it should be fine to use a residential pressure washer though I would be hesitant to use it indoors because there are so many things it could damage.
Thank you so much for this information. What you said makes tons of sense. I will use the hose with extension pole brush to clean the siding. You save me from a future headache!
Looking for a way to clean a second-story stucco wall. Have tried an ineffective hose-attached washing solution and pressure washing. Problem is access. Would need to walk on a 14 year old roof to get close enough to the wall. Any suggestions?
I use a large stiff bristle brush on an extension pole.
Thanks, Scott.
On stucco, if the brush doesnt work you could use a telescoping wand or an extension pole for your wand and a quick connecting pivoting coupler. Dont spray any cracks or chips unless you patch them first and then you have to wait a week before you pressure wash. I wouldnt get the tip any closer than 2 Ft. unless you are using low pressure. Oh and another thing to remember when washing stucco make sure you alays pre wet the surface before washing so the dirt rolls off easier dry stucco like to grab the dirty water rolling off.
Good luck
Thanks, James.
Very good advice here, allot of people dont know how to pressure wash. I used to pressure wash professionally, and we would not pressure wash any wood siding unless they were going to paint it. Then we would use really low pressure and deck brushes with very long extenda poles, and the man on the wand would only shoot the house at a (low pressure) downward angle. If we were on a vinyl job we would mainly use the deck brushes and medium pressure shooting the water downwards and angle towards the overlap. If we couldnt use a jlg lift we would use ladders and ladders with scafolding planks. If we couldnt do it safely then we would have to turn the job down.
I have been living in my vinly sided house for over 20 years and I have probably pressure wahed the entire house like 8 times. I just last year replaced my bedroom window with a sliding double glass door and guess what everything under my siding was completely dry and mold free. You just have to know what your doing.
You never want to shoot vinyl siding from below because they have drain holes all over and you will shoot water right up in there. You never want to shoot vinyl towards the underlap or you will be shooting water right under the siding. On wood siding you never want to shoot it straight on because all the joints or cowboyed together and you never shoot it from the bottom either or it will go straight up under the wood siding.
We turned down quite a few wood siding jobs because some home owner/diy’er or painters that didnt know what they doing chaulked all the over laps, which causes big problems because the water has no where to drain from rain and the wood will start to deteriorate and mold behind the siding.
Anyway good luck to all and all there power washing needs
L8rs
What about pressure washing the exterior of a house that has areas of mold, but underneath, the paint job, we’ve been told, is still good–is power-washing okay, and is there a way to do it without damaging the paint? Power washing was done two years ago, but the mold is back, and a 5-year old paint job (at that time) had some areas where the paint was stripped exposing the wood.
Help! What can you do if a painter DID powerwash your wood siding house, and blasted off tons of paint chips that did show to have lead?
Best you can do is clean up the paint chips and wait for everything to dry thoroughly before repainting.
What about a vinyl sided house that not tyvek wrapped?
I’d like to know the response to this question as well! I live in Pennsylvania, I am a widow and on my own, I put in a modular home three years ago and this summer I noticed a slight film of black on the vinyl. Help! This is my life-end home and needs to last for me for years to come!
What is your opinion on pressure washing a house that has paint in some areas? Without having the paint chip off as well as the psi power?
Under 1200 psi if you can.