When is the Best Time to Pressure Wash?
The Top 10 Pressure Washing mistakes- Exterior Home Painting
All paint manufacturers say about the same thing when it comes to surface prep, more or less – Clean, Dry, Dull. That means in addition to all your scraping, sanding and prepping and filling and caulking, you need to clean the surfaces, that’s usually pressure washing.
The question is: when is the best time to pressure wash, before prep begins or after prep is done?
Answer: it depends on the project. To illustrate, using my favorite orange house, which was built in about 2006, so there wasn’t any old peeling paint to scrape & sand away. In this case the prep amounted to removing old caulk seams that had buckled, re-caulking, followed by very thorough washing.
Another favorite house, which is about 100 years old, required lots of aggressive surface prep, sanding too – all of which created a lot of dust. So, in this case the best time to wash would be after the dust making was done because dust is an adhesion inhibitor and needs to be removed from the surface before painting.
But first, caulking has to be in place or water will get inside and cause problems. So this process is a little less convenient and that’s why most painters don’t do it.
Sometimes old paint begins to break down (especially cheap paint with a lot of clay in it) and become chalky. This chalkiness needs to be addressed either by washing and scrubbing with brushes, or priming with a clear binding primer, or both.
Other cleaning observations involving use of pressure washers; it’s easy to cause damage using one of these machines, it’s also common for companies to put the new guys on the washer. This is like giving the keys to an F-350 or a Porsche to a brand new driver – it’s too much power for the experience level and something is going to go wrong.
The top 10 most common pressure washing mistakes:
#1: not washing 100% of the surfaces. Just because it’s wet, doesn’t mean it got washed.
#2: getting too close to the surface, causing cuts and scars, and on decks blowing out the soft-grain of the wood, leaving washing-board surface – requiring wood replacement.
#3: staying too far away for the pressure to be effective – after damaging the last house by getting too close, he’s going to make sure he doesn’t damage this one by staying a couple feet away.
#4: getting water inside the house; either by blowing water up inside soffit vents – this gets insulation wet in an area that doesn’t dry, resulting in mold growth and water stains as the moisture evacuates the cavity. Or, not ensuring the windows are closed.
#5: washing from the bottom up – this is common sense but that doesn’t mean common to everyone. Washing from the top down ensures that the dust and dirt from the top gets washed off as you descend.
#6: washing from the ground – not using ladders but instead a “focus” tip, this is just lazy, sorry.
#7: using the wrong tip in the wand. There are a dozen or so common tips, and one of them is perfect for the application.
#8: Trying to use the pressure washer to wash windows…nuff said.
#9: Grass burn – leaving the machine in one spot on the lawn for too long, burning a little square into the grass.
#10: magic number 10 is injury to the operator. The most common is pressure cut in the skin, usually the back of the calf as the operator swings the wand behind him to wash the surface on the other side of the ladder.
These mistakes are much more common with sub-contractor brokerages (sub shops) than with employee companies. Contractors whose business model is sub-contractor brokerage don’t train their subs, period. Many employee-model companies don’t either, but tend to have more training than sub shops.
There’s great resources on proper washing, check it out.