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nightman 01-19-2008 12:59 AM

Pressure washing painted houses
I need your help with cleaning solutions to use to pressure a house before I paint it again.

joewho 01-19-2008 01:05 AM

Can you be more specific? Are you looking for chemicals to use? What type of siding do you have?

typically, a mix of tsp, a little bleach and a little soap does very well.

Nothing works better than hand scrubbing, but it's perfectly acceptable to use the sipohon on the pressure washer to apply the cleaner. Let it sit and then power wash.

nightman 01-19-2008 01:10 AM

It's just a painted wood house that I want to prep before I repaint. However I want to use a pressure washer to do it. So I'm looking for a cleaning solution to use through the PW.

justdon 01-19-2008 11:50 AM

Dont pressure wash
30 years ago I thought I was doing it right too,,,pressure washed a house,,,BAD deal,,it roughed the siding where it was at all soft. Didnt touch where paint was hard. ALL the soft spots are now rotted out and I have to replace all siding very soon.

I have seen MORE trainwrecks pressure washing a house than not. Today their are the gentla spray on,hose off cleaners,,,thats good enough. Scrape as needed. No matter WHAT you do if the paint is peeling NOW it is going to peel again!! Have seen some BURN all the paint off,mixed results also. Incompatible paint types underneath leads to constant peeling.

Strongly consider siding(new) to reduce or eliminate the paint jobs. Worst part is most painters only put one coat on,that doesnt last long,,,should be bare spots primed,and then TWO full coats over that to look decent for more than a couple years.

If you DIY the trim and window replacemnet FIRST is the most expensive part by far!!Of siding a house,siding is cheapest part.

But to end a long story,wouldnt pressure wash a house again,,,they take a LONG time to dry excess moisture out to paint,,,like months with good DRY weather,,low humidity. You WILL wreck more than you gain!!

HenryBockman 02-03-2008 03:35 PM

Here is an article I wrote about pressure washing houses that may help those that want to pressure wash thier own house.

The Art Of Power Washing Houses

Power washing siding may seem safer to take on yourself, but if you don't have the proper tools and experience it could cost far more than you intended.
Some of the most common mistakes to avoid made by homeowners and contractors are:
Trying to remove the powdery coating called oxidation on aluminum siding. Removing this coating can cause discoloration and in some cases cause the siding to look like a completely different color.
Using too much pressure can also force water up behind the siding where it will cause mildew behind the siding or in some cases, blow the siding off the house!
Washing the house from the top down or letting chemicals dry on the house, which may leave streaks on the siding.
Using a ladder to clean the upper areas of a house can result in serious injuries and death from slipping off the ladder.
These are the types of mishaps that many people have when attempting to do a quick power washing of their home. If you decide to use a power washer on your home, here are some general guidelines to use.
Make sure the machine your using puts out a minimum of 4 gallons of water per minute and less than 1000 PSI.
Most homeowners will buy a machine from a hardware store that puts out 1,000 PSI but only uses 2 gallons per minute of water. While this machine may work, it will triple the amount of time to do the job properly.
Be careful if your making your own house washing chemicals. For example, mixing bleach and ammonia can create a poisonous gas.
We suggest that home owners buy a siding wash that's available in most hardware stores and follow the manufactures guidelines for the product. Leave the stronger agents to the pro's or you may end up removing the paint along with the dirt!
The best way to clean siding is by using a power washer that has a chemical injector built into the machine. Using a chemical injector will allow you to pull the soap from the container, mixing it in the machine with water and spray it onto the house using low pressure starting from the bottom up. Make sure when using a power washer that you don't shoot water or chemicals up under the siding, this can cause significant mold problems behind your siding.
Allow the chemical to dwell on the siding, then using low pressure, rinse the product from the siding. Make sure when your rinsing the product off the siding that you start at one end of the siding all the way to the end. Do not stop or vary your distance from the siding, or it will cause the surface to be cleaned un-evenly.
If your siding has small black dots that do not come off during cleaning but can be scraped off using your finger nail. You probably have artillery fungus on your siding. This can not be removed from the siding without causing damage. For more information on Artillery fungus, see the Artillery fungus page.

If you decide this project is more than you want to handle on your own, we would be happy to tell you how to do the job safely and correctly or to find a reputable and experienced company for power washing siding, just give us a call.

Henry Bockman
President, Henry's Housework Inc.
MHIC # 65039 Licensed, bonded and insured.
301 216-9675

troubleseeker 02-03-2008 07:20 PM


Originally Posted by nightman (Post 89833)
It's just a painted wood house that I want to prep before I repaint. However I want to use a pressure washer to do it. So I'm looking for a cleaning solution to use through the PW.

Power washers and wood siding...second only to electric drills with sanding discs chucked in them for the amount of wood siding they have f**ked up.:yes:

Barry M 02-05-2008 08:23 AM

Pressure washers don't screw up wood, uneducated people using a pressure washer does. Too much pressure is almost always the culprit of damage, most think the "pressure" is what does the cleaning, when in reality it's the chemicals that clean.

Washing your wood siding properly isn't going to force anymore moisture in the wood than a rain storm would. So whether its been washed or been rained on regardless you obviously have to let the wood dry out or get to the proper moisture content before attempting to paint it.

Using a pressure washer to remove loose paint isn't a good idea unless you are experienced. Again, too much pressure will shred the wood and cause soft spots. Besides, even after using a pressure washer for prepping you can ask any experienced painter that some scraping is still necessary.

I don't recommend a DIYer to attempt washing and painting their own house. There is much more to it than blasting it and re-painting.

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