Power Washing and Roof Cleaning Forum

People with more experience than me can tell you better, but I believe that is oxidation. I have a couple of vinyl houses coming up where they have this condition, and have been researching it lately. I've read that in most cases you need to brush the house with the same type of chemical that you use for gutter whitening to remove it... F-13 is one I've seen that has had success, and what I am going to use.

I read where some people had success just downstreaming F-13, or using it with an Xjet... some downstreamed it straight, some cut it 50/50. Most often i read about people brushing it, though.

Often the blotchy condition arises when people use too much pressure rinsing, and accidentally remove some of the oxidation... although I imagine sometimes it may get disturbed even with gentle pressure.

This is in the Certainteed siding Warranty.  Give her a copy of it and the Insurance company also. You did nothing but wash the house and expose the oxidation. The homeowner failed to maintain the siding and she is trying to blame you.  If the siding manufacture doesn't warranty  the siding. Nether do you!

Failure of owner to provide normal maintenance and cleaning; • Normal weathering, fading, chalking or oxidation; • Discoloration or other damage caused by air pollution 

 https://www.certainteed.com/resources/CTS230.pdf 

Dave,

How much area are we talking about? Perhaps it's just better to brush it and then move forward. This will satisfy the customer as long as a thorough job is done. She won't be leaving you a negative review. Which is more important to you.

Hank

It WILLl look blotchy and inconsistent when you are dealing with Oxidation....only thing you could do is brush it out and remove the oxidation.  

 

This is part of every quote when oxidation is involved....

Oxidized surfaces should never be cleaned using high pressure.  This can cause striping, uneven cleaning, and damage to the surface.  Our Soft Wash non pressure cleaning process is used to remove Algae and other Organic stains and as little of the oxidation as possible. As the surface dries after cleaning, and due to this pre-existing condition, oxidized or faded areas may reveal stains underneath weep holes of siding, irregular spotting of the surface and other surface irregularities.  While the surface will be clean, we cannot guarantee the final outcome or be responsible for these inconsistencies. 

 

Thank you all for your words of wisdom and experience. This is one of those lessons that comes from experience. I will add the recommended disclaimer to my quotes. For this job, we will go back with one of the recommended cleaners and a brush in order to meet the owner's expectations. This demonstrates once again the value of the NSWA forum; solutions for those in a jamb and warnings on how to mitigate such potential jamb!

Guess what. The owner emailed me the other day and stated the blemishes have faded away and the siding looks great. Well that was an answer to pray. BTW I revised our soft washing disclaimer as follows:

Apply soft-wash process to exterior of house to remediate algae, mildew and mold growing on it. Then rinse to remove the green and black discoloration as well as any dirt.
We do not use a pressure washer and you should never let anyone use one on your siding. Our sprayer uses a pressure less than a typical garden hose. A pressure washer may force water through the siding laps. This may result in mold between the siding and house. Pressure washing may also leave streaks and even cause damage to the finished surface. Lastly pressure washing only blasts away the growth. Our soft-wash cleaner actually remediates the organisms so they don't just grow right back.
Concerning painted aluminum, please note at times dark spots and streaks that appear on painted aluminum materials is not mildew but is oxide leaching through the paint. Our cleaner does not remove oxide.
Please note that even vinyl siding can have oxidation, especially if it is aged. Oxidation causes vinyl siding to look faded, white or chalky. This chalk is actually Titanium Dioxide being released as the vinyl degrades from UV exposure. Soft washing or pressure washing does NOT remove this oxidation. If oxidation is present, the siding may have a faint blotchy / spotty appearance after cleaning and should fade away within a couple of weeks or so. In order to remove the oxidation, a different cleaning agent would need to be applied and the vinyl siding scrubbed with a brush. This is not included in this quote.

-- Edited by Dave O on Wednesday 9th of May 2018 08:16:10 AM

Dave, I was going to say that you might wait a day or two and see what happens. Sometimes they will "look even" after they fully dry out. This is also where a "soft wash" really plays out. Any pressure on oxidation can cause a "splotchy" appearance and when I say pressure I mean even house water pressure can remove oxidation.