Black stains on vinyl siding (C) Daniel Friedman Vinyl Siding Stain Cleaning FAQs

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Vinyl siding stain cleaning procedures, chemicals, products:

This article series discusses common causes of stains or discoloration found on vinyl building siding. Distinguishing the type of stain found on siding is useful in deciding on the cause and thus the cure or prevention of staining

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

FAQs on How to Clean or Remove Stains on Vinyl Siding

Leak stains on exterior vinyl sided wall (C) Daniel FriedmanThese vinyl siding stains and vinyl siding cleaning diagnostic questions & replies were posted originally at VINYL SIDING STAINS

Watch out: when power-washing siding do not spray "up" such that water is forced underneath or behind the siding or you may cause serious leaks into building walls, in turn cause wet insulation or wall cavity mold contamination.

Also take care that power washing some siding materials such as soft cedar shingles and wood clapboards from too-close a distance can cut into and damage the siding leaving marks that are hard to remove.

Finally, do not power-wash asbestos-cement siding or roofing products aggressively or you may create an asbetstos sludge and later dust hazard.

Watch out: don't use solvents such as acetone, lacquer thinner, or mineral spirits to clean vinyl siding. They can dissolve and permanently-disfigure vinyl and other plastics.

Question: how can I remove the spots left on my siding after I had it cleaned?

Just sent you an e mail about my problem and this is the follow up pictures. We will have to reside our entire house if this issue is not solved as it is right by our doorbell and front door and it extensive in this area. I would really appreciate your ideas as to the caused. I have contacted the company to have it cleaned again and it did not change. ... Anonymous by private email 2017/06/10


I can't say for sure what the problem is with the yellowish stains I see on white vertical trim and darker stains I see on grey-beige vinyl siding in your photo. I suspect that a cleaner containing a bleaching agent may have been sprayed or over-sprayed onto a surface while working nearby, then let sit too long without actual washing-off.

Your question prompted me to prepare a researched answer in some detail that I hope will be useful and that I'll publish at VINYL SIDING CLEANING METHODS

On 2017-05-25 by (mod) re: what are the common chemicals found in siding cleaners & how might using a cleaner leave new stains or marks on vinyl siding?


Can you tell me what chemical was used in the siding wash? Here are some common siding cleaner chemical ingredient examples based on looking at the MSDS sheet for the product. When you tell me what cleaner was used we can understand its properties.

If portions of the siding are discolored even after drying completely there can be various causes, not all of which would be the fault of the cleaner nor cleaning process.

See VINYL SIDING CLEANING METHODS for an explanation of why using a cleaner on vinyl siding may result in new spots or streaks on the wall or trim surfaces.

On 2017-05-25 by siding girl

I had my home pressure washed and on some parts of the vinyl siding it turned a dark purple color, same chemicals was used on all of the house and only one are changed colors. what could that be from?

On 2017-02-16 by (mod) re: pink stains on siding

Pink stains on siding could be mold but more-often an algae. Mold and algae both produce growths in a very large range of colours.

A repair might indeed make siding colors different on a building, but the color difference would be uniform within an individual piece of siding up against another; stains from algae or mold will have irregular edges and patterns and will usually match shaded or damp areas of the walls.

On 2017-02-16 by Susan

I have recently moved into a home built in 1947 with white siding on the garage and kitchenette. Some parts of the white siding look pink! Friends have said it's probably mold but I thought mold was black/greenish. Around the back of the garage the first 5 panels are pink and all the lower panels are white. Do you think at some point someone repaired the siding with two different types of panels?

On 2016-10-28 by (mod) re: algae stains on siding: causes

Typically algae forms on siding in shade and where it's damp.

You can power-wash but watch out for some inexperienced worker who blows water into the building walls by careless power washer aim.

On 2016-10-27 by Jessie

My siding is not over five years old and within the last year or two I noticed green algae forming on the siding on the side of the house and brown stuff on the front of the house. Not sure what is causing this and should I have the areas affected by the algae power washed?

On 2016-10-28 by (mod) re: what is the yellow and black stuff on my vinyl siding?

I can't know from just your e-text Rachelle, but common yellow stuff on siding is pollen and black stuff may be dirt, road dust, algae, mold. If it's actually hairy and not a leftover from vines growing on the surface I suspect it's a mold growth or a dried out algae or moss. When such stains appear suddenly I'm baffled too but would look for a source of mold growth, artillery fungs, or from an event that could have left soot such as a nearby fire.

On 2016-09-20 by Rachelle

This unknown black growth appeared over night on my siding. Starts off yellow then black when I removed it it was like brown dust & hairy. What is this.


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