Power Washing Tips  & Most FAQ’s

With 30 years of experience as a painting contractor, I will give my power washing tips and tricks so you can have the same results as if you hired Klappenberger & Son to power wash your house. 

Is it necessary to power wash a house prior to painting?

Yes, it is wise to have a clean surface so the paint can grab a hold and last as long as possible. 

Can you power wash wood siding? Yes, and it is best to use the least amount of pressure and let the chemicals do the work. Generally, Klappenberger & Son sets the power washer pressure to 1,500 psi. Damage is more likely to occur when the PSI exceeds over 2,300 PSI. 

power washing to hard can cause the wood to look like it gets hair

PSI over 3,000 is at a hazardous level. However, power washing hard surfaces like brick and concrete can easily handle 3,000 psi as long as they are stable.  Pressure washing wood siding, decks, and fences can easily shred softwood, as shown in this photo.



 Power washing tip #1

 This is my favorite power washing tip.  Keep the pressure low and let the chemicals do the work.



Should I remove the screens before pressure washing? Yes.  Screens older than ten years old start to lose their integrity.  Even a soft power washing or standard hose nozzle can cause damage.  Removing the screens allows the dirt trapped on the windowsill to leave and saves your screens.


Power washing tip #2

Removing screens. 

Man power washing side of building

Best Cleaning Solution for Power Washing

What is the best cleaning solution to use when pressure washing a home? Bleach and liquid soap detergent make a great combination. A liquid detergent such as Dawn will help loosen up the dirt and thicken up the cleaning solution. The bleach kills the mold and mildew. A second benefit of using liquid detergent and bleach is it thickens up the cleaning solution. When running the solution through the power washer, it will stick to the house longer. Using pre-made products from the store work but will cost more.

Nothing kills mildew better than chlorine. Bleach is very inexpensive, and so is the liquid detergent. Most pre-made products sold in stores also require bleach to kill the mold and mildew.  Their product doesn’t do the heavy lifting.

What are the proportions in the cleaner? In a clean five-gallon bucket, add 3 gallons of bleach and 1 cup of liquid soap. Place the chemical injector hose in the bucket and open up the valve ¾ of the way. Turn the chemical adjuster so you have a one-part cleaner and four-parts fresh water.

cleaning solution for power washing

           Bleach for power washing


 Power washing tip #3

Bleach is your best cleaner.

vinyl siding with cleaning solution

Power washing tip #4

Let the chemicals do the work. 

How to pressure wash aluminum and vinyl siding? Klappenberger & Son has cleaned over 15,000 homes in Maryland, DC, and Virginia. We have developed an excellent system for power washing a house. 

Our philosophy is to let the chemicals do the work, not hard-damaging water pressure.  It takes only a couple of minutes to see that the mildew on your house is disappearing. 

Most contractors allow the cleaning solution to sit on the house for a few minutes.   Even though mold looks like it is 100% killed, it is not.  Mold spores can survive the concentration of bleach for up to 15 minutes. 

Letting the solution sit for less than 15 minutes allows the spores to regrow back.



Power washing Tip #5 

Keep the chemicals wet and give them time to work.  


Power Washing Tips – Don’t Do This 

Can you power wash windows?  Yes, when pressure washing your home, windows can be power washed, but there is a potential problem. If the windows are open, the water gets in.

At Klappenberger & Son, we only power wash when the windows are securely shut. All kidding aside, there is a serious issue to consider that is less obvious. Do not let the bleach and cleaning solution dry on the windows.

If it does, it can damage the glass. Chlorine is an acid, and it can etch the glass if it dries. Keep the solution wet at all times. It is not necessary to cover the windows with tape and plastic. Just do not let the chlorine dry.


Power washing tip #6

Do not let the bleach dry in the windows.

keep chemicals from drying on windows

Does Power washing take the place of cleaning the windows? No. Some window cleaning products can be applied through a pressure washer, but I have not found any to recommend.  If you know of any good window cleaning products, please let me know.

Will bleach hurt my plants or grass? No. Not if you stick the recommended ratio of cleaner to water.

Can I power wash a house with just water? Technically yes, but it’s not practical.  You can clean dishes without detergent, but it would take a lot longer and would not be practical.  It also would not kill the bacteria etc. The same is true for your home.  Pressure washing without chemicals leaves no choice but to increase the PSI.  Increasing the PSI increases the chances of damage and slows the time it takes to clean.


What Does It Cost to Have My House Pressure Washed?

 The standard price to power wash a home properly is about $300.00 – $500.00. Several factors can influence the cost of power washing a home, such as:

  • length
  • height
  • the difficulty of terrain (slopping land, etc.)
  • adding the deck

Some companies charge only $200.00 because they do not take the time to let the cleaning solution work.  The cleaning solution did not have enough to kill the spores before it was rinsed off.   It is a classic case of “you get what you pay for.” Please see the question above called “How to power wash house and siding” for more info.


FAQ about Power Washing

When should I Powerwash a house? The north side of a home gets the least amount of sunshine and the most mold.  Therefore, the northern side can require power washing every 2-3 years. The other remaining areas will probably not need power washing for 4-6 years.moldy siding

The exterior surface also plays a role in how often a house needs to be power washed.  Vinyl siding and other petroleum products are preferred surfaces for mold to grow.  An oil-based stain or paint is the perfect surface for black mold and will require frequent power washing.

How to power wash a house before painting? The goal of power washing is to get the surface clean so the paint or primer adheres.  Pressure washing should not be in replace hand scraping.  However, the pressure washing should be done first, with one exception.  The exception would be on a home with lead paint.   Why? Because water will get between the bare wood and the paint and lift the edges that were once tight to the wood.    

Can I power wash a house with led paint? Yes, but your procedure should be a little different. If you have lead paint on your home, scrape first and then power wash.  It is crucial to contain the lead paint chips and dispose of them properly.   After removing the loose paint chips, power washes the house using the cleaner and low pressure.  There are specific protocols for working with lead paint on homes.  Not following the procedures can result in fines in the $35,000 range per violation.  I strongly suggest taking a  led abatement course to avoid stiff penalties.

Power washing Tip #7

This is the least known power washing tip.  The cleaning solution must be applied from the bottom up.   Applying the answer from the top down leads to missed areas.  Applying the chemicals from the bottom and working your way up ensures that all surfaces are clean.    Once the bleach and liquid soap sit on the surface for 20 minutes, rinse from the top down.

Is it safe to power wash a house with higher psi? Yes, and if the brick and mortar are in good shape, increase the PSI to the 2500 – 2800 range.

Weather Conditions

Can you Powerwash a house in the winter? Yes, “and it’s hard if it hits on your nose.” Sorry, I had to quote a little Frank Zappa. If it is below 50 degrees, pressure washing your home turns into a miserable job.  If it is below freezing, make sure the hose does not have frozen water trapped inside because it can damage the pressure washer.

Can you power wash a house in the rain? Yes, that is a good time to do so because the cleaning solution will not dry quickly. Whatever rain hits the siding will not significantly dilute the cleaning solution.

Tips and Tricks for Power Washing Wood Decks and Fences

Any tips to power washing a wood deck or fence that is untreated? Wood decks made out of redwood, treated lumber, or cedar are softwoods. It is critical to power wash with minimum PSI.  Increasing the PSI is tempting because you can quickly see the results.  Sometimes raising the psi is the only option, and you hope no damage occurs.  Before you do, try two things first.

Raise the bleach concentration to 25% bleach and 75% water, and let that stand on the deck surface for 20 minutes, making sure the bleach stays very wet.

Apply wood brightener with a pump sprayer (it will not work through a power washer). Allow it to sit for the recommended time before gently pressure washing off.

You will not be able to see the actual results until the wood is dry.  The results of using bleach and wood brightener are very effective.

Any tips to power washing a deck or fence if it has had a wood preservative applied before? Follow the same steps as listed in the previous answer. You will find that a significant portion of the previous coating will be back to bare wood.

Power washing a deck

Can I power wash my gutters and get them back to their original bright white? No. The only method I have found that works are using cleaners specifically made to clean gutters.  These products through the spray and wiping off with a rag.

Who can power wash my house near me?

Klappenberger & Son has been power washing homes in the Maryland, VA, and DC area, so chances are we can powerwash near you.  We follow all the best practices listed above. We are currently serving:

AnnapolisDavidsonvilleSeverna ParkCrofton
ColumbiaEllicott CityRockvilleGaithersburg
BowieBaltimoreTowsonOwings Mills
CockeysvilleBuckeystownMt. AiryClarksville
GeorgetownWashington DCChevy ChaseFairfax
RestonSpringfieldLeesburgTysons Corner