Pressure Washing an Old Home

How to Pressure Wash Wood SidingUsing a pressure washer on an old home is not as simple as you might think. While it may be a great way to clean dirty siding and prep for new paint, if not done properly it can cause more harm than good.

You can cause damage to wood or older soft masonry and force water into the structure of your old house. So to help you prevent this, I put together a quick primer on using a pressure washer properly to protect your biggest investment.

How to Pressure Wash a House

  1. Don’t Get Too Close - This is the number one problem with pressure washing a house. People put the nozzle right against the surface to get those stubborn stains. Inevitably, this will dig out portions of the wood or mortar and ruin perfectly good siding. Stay at least 1 foot away from the surface at all times.
  2. Pressure Washer Damaged WoodPhoto by Jon Chapman

    Pressure Washer Damaged Wood
    Photo by Jon Chapman

    Use a Lower Strength Washer - Some commercial pressure washers are way to powerful to be used on an old wood house. They may be perfect for cleaning driveways, but they will blast right through wood siding especially if there is any wood rot. I prefer a 1500 psi pressure washer. Even if I slip up I won’t cause nearly as much damage as a powerful commercial washer.

  3. Keep the Stream Wide - Many pressure washers have an adjustable nozzle that allows you to make the stream of water go from a wide fan all the way down to a single jet stream of water. That jet stream can dig a hole through asphalt! Don’t even think about using it on your house.
  4. Use Vinegar For Mildew - White vinegar is a great cleaner around the house and it is a natural choice for cleaning mildew off the exterior of your house. Put it in a spray bottle and apply it in small sections. Let it sit about 30 seconds to 1 minute and then use the pressure washer to rinse it away.
  5. Scrub, Scrub, Scrub - For the really stubborn areas the best you can do is give up on the pressure washer and use a strong scrub brush with soap and water. Screw one on a extension pole to reach those hard to get areas.
  6. Keep Good Aim - If you aren’t careful with your aim you can shoot pressurized water up under the clapboards or shingles and into the walls. And there are plenty of things inside your walls that don’t react well to pressurized water. Try to wash downward along the natural path that water from rainfall would take.
  7. Let it Dry - Once you’re finished pressure washing if you plan to paint make sure you give the house ample time to dry out. Painting wet wood is a great way to waste money on a paint job that won’t last. Depending on your climate 12-24 hrs probably isn’t enough. 48 hrs is a safer bet, but you’ll never have a problem from waiting too long.

Follow these simple rules and you shouldn’t run into any big surprises when you go back to examine your work.

 

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by Scott Sidler

I'm a historic preservationist and author. I help old house lovers understand & restore their homes so they can enjoy the history and character that surrounds them more everyday! When not working, writing or teaching about old houses I spend most of my time fixing up my own 1929 bungalow with my wife Delores and son Charley.

http://www.austinhomerestorations.com

27 comments

  1. Good advice. Green and safe chemicals for pressure washing too!

  2. My old house got pressure washed last summer. The exterior is awesomely beautiful! Now it looks like a new built house.

    • Glad they did a good job! Always nice to know you hired a pro.

  3. Richie on said:

    I really love your website;thank you so much for the wonderful advice.

  4. Sound advice Scott. It never fails to amaze me how many people blast away with their pressure washer with no regard for the damage they may be doing to their property.

    I learned to cut down on the pressure and stand back when my first venture with a pressure washer left me soaked from head to toe!

    • Eve, it’s a messy business pressure washing! ;-) Thanks!

  5. James Keller on said:

    Would you pressure wash a 107-year old house with wooden shake and stucco exterior prior to painting?

    • I would, but follow the ideas I outlined in the post. That should protect you from any damage.

    • Ann HK on said:

      Appreciate someone in my camp. House is 1907 stucco lower with cedar shakes above. Winning bidder (house is family home, but not ours and not our selection) says they will be using pressure washing. Unless they’re highly skilled, I do fear there will be more damage than good. Restoration and quick are not synonyms!

      • Indeed Ann. Honestly nothing works better than soap, water and stiff bristle brush to clean an old house. We do it all the time. It takes longer but there is no chance of damage like with pressure washing.

  6. Great page. Just a bit of info, you can have as big of a pressure washer you want, as long as you have the right nozzles, you can achieve the desired pressure.
    I have a 4000 psi commercial machine which is perfect for concrete but when I was houses or buildings, I have a nozzle that lowers the pressure to less than 150 psi… so low you can stick your hand out front.

  7. George Fenn on said:

    Scott,

    I have a 1913 farmhouse in excellent shape, but the late 1970s or early 1980s vintage white siding is pretty dirty. When my engineering-oriented Dad was alive he was reluctant to power wash for fear that the water would become trapped beneath the siding. (Good, craftsman-like) builders I’ve spoken with say if you power wash with common sense, that isn’t a concern. But I’m still concerned, especially keeping in mind that it is approx. 35 year-old siding. What are your thoughts? Thanks.

    • George, it depends what the siding is and how it was installed.

  8. George Fenn on said:

    p.s. I should have been more clear in my last post, this is, I believe, VINYL siding installed around 1980 (installed because my parents didn’t want to have to repaint their beautiful white farmhouse every 10 to 12 years).

  9. Robert on said:

    Wow, thank you so much for this article. My aunt has a home built just over 100 years ago, and with spring here and summer coming, I know she’s been thinking about getting rid of a lot of grime that has collected on it over the years.

    I think a pressure washer will be great for her, but admittedly hadn’t thought too much about how washers can negatively impact your old home.

    She mostly has siding on the house, however, so it’s not wood like the pictures here. Although, I wouldn’t be surprised if there’s wood underneath that siding. Are there specific pressure washers you recommend that are best for homes with siding?

    Thanks.

    • Really just any pressure washer that has a lower pressure setting of under 1500 psi should work fine. Any higher than that and you can start to do damage. 1000 to 1500 psi is a good range.

  10. ralph on said:

    I have a problem with this advice, at least as applied to my situation.
    When we bought this house seven years ago, in the inspection dry rot was discovered on the south side that was so serious that the concrete siding and underlaiment had to be replaced at a cost of $8000 – paid by the seller. The contractor said that water had gotten up underneath the siding, which is constructed to protect against water falling normally, like the usual rainfall, but when forced upward by wind or pressure hose it gets beneath the siding and rots underlaiment. Now I want to have the moss cleaned off the north side of the house. My wife wants to have it pressure washed. I say no. What do you say?

    • Ralph, if you follow the steps I laid out in the post you shouldn’t have any issues. Most painters pressure wash a house incorrectly which causes the water to get pushed into the wrong places. Use a low pressure setting and always wash at a downward angle. Those are the important points. But follow the whole list and you should be fine. As with any advice proceed at your own risk. But that is what I would do if it was my house.

      • Steve Mills on said:

        How do you pressure wash at a downward angle without scaffolding or bucket truck? Kind of hard to pressure wash on a ladder. Is there a wand attachment to help get the right downward angle?

        • We use a ladder for almost all our pressure washing unless we’re dealing with 3 story or taller houses. Even if you are aiming horizontal you should be relatively safe if the pressure is low (under 1500 psi). Just be careful when you’re up high no matter what you’re doing. Falls are far too common on job sites.

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