Mold Resurfacing

I washed a house Nov 15th with the usual mold & mildew on the Eve’s & facial boards. All areas washed were white painted wood surfaces. House cleaned up very nice & customer was pleased. They called me back today saying the house is covered in mold again… Has anyone experienced this before this quick? Wash mix was was 12.5 sh with elemonator. Any advice would be much appreciated…

where are you located?

South carolina

What is needed to create a prime mold/algae growing environment?

What is the mix ratio Water:SH?

How was it applied to the surface?

3 gal sh 2 water down streamed

what is your draw rate set at for your downstreamer? how many gallons of mix did you use for how many sf of the house? how long dwell time, what was the temp at time of application - was it cold out?

Just thinking out loud, I wonder if they used crap paint, or perhaps interior
instead of exterior paint. You say all the areas washed were white painted
wood surface? I think some one might have painted wood with out a proper
wood cleaning carried out before painting. Just a thought.

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we used ab 6 gal of mix for this house. It was probably ab 3000 sqft… We had to soap couple areas twice. It was a little cool that morning(maybe 45) but warmed up mid morning.

I am starting to think the same, because I washed similar houses around this same time with no problems…

Sorry I missed that part about this being painted wood… more than likely that is whats going on - I have seen it happen numerous times - where the mold is actually coming through the paint - and the wood itself is actually where the spores area because it was not properly cleaned and primed…

Besides running a Roof/Power washing company, an air diaphragm pump rebuilding and sales company, and an insulation removal company…I’ve owned a Mold remediation and testing company for 16 years and hold CRMI, and MRS certificates.

Here is likely what happened…you didn’t kill the mold. Bleach is not effective at killing mold on a porous surface due to the nature of both the SH as well as the way the organism lives. This is why there is no EPA registration number on a bottle of bleach as a fungicide and it is not recognized as a fungicide and is not used for anything other than stain removal in the mitigation industry.

It is likely you removed the surface growth, but left the Hyphae (roots) in the structure. After the chlorine evaporated off, what remained was water which fed the roots of the mold.

If you are doing a repaint, then prior to a surface cleaning, while dry, the house should be sprayed with a Quaternary Ammonium or other EPA registered Fungicide. That will actually kill the mold organisms on the wood. Afterwards, the house can be surfaced cleaned to get rid of the staining. They should not immediately follow one another as the Quat will react with the ammonium salts to make bad things you don’t want to breath.

All this is predicated on making certain there isn’t an underlying moisture issue and there isn’t excess moisture behind the boards causing excessive growth.

Treatment for this is to hit it with a fungicide, then use a top quality mold resistant exterior paint (NOT an additive). Do a test area first to make sure it stays mold free. In extreme cases, we’ve had to soda blast the paint off then treat the surface or replace the eaves boards. We will sometimes follow up on sheltered areas with a clear, breathable anti fungal coating as the final coat.

Here is an interesting read for anyone interested: blacktoxicmolds.com

Then the homeowner needs a painter not a pressure washing company

The black toxic molds thing…what you will find on the outside of a house will NOT be Stachybotrys. This is very often used to scare people. Just because it is black, doesn’t mean it is Stachy. The world’s most common mold is Cladosporium…it is also black. Not a week goes by when I get a call from a panicking mother who saw some black mold growing in her vinyl window and is scared to death.

Why won’t it be Stachybotrys? Stachybotry is hydrophilic and very delicate. It needs a very stable, very wet environment to grow in. The interior of a leaking wall cavity is ideal. The exterior surface of a house is about as polar opposite of that as it gets.

Second, while I’ve dealt with tons of Stachy in my career, and it is something to take very seriously when it is there and I’ve had clients become VERY sick from it, it is also amongst the rarer species of molds.

Last but not least, molds which grow on the exterior surface of a house are not typically a health hazard. With the exception of contact dermatitis from some high toxicity species or somebody who is hyper allergic, only molds which grow on the inside are usually a concern from a health standpoint. This is because in order for you to become ill, you need to breath a certain quantity of the mycotoxin bearing spores in. Mold spores are measured in Microns and even the slightest breeze will easily dissipate them. This is why it would be rare that the exterior molds would be in a situation where the spore and mycotoxin levels would be built up enough to affect your health. On the inside is a different matter. Closed environment.

However, mold growing on the outside is an indicator of a moisture issue. It should be investigated as to whether that moisture translates into the interior structure.

As for using a painter vs a pressure washing company…if there is a serious mold concern, then you need a mold remediation contractor. Why? Take a look at your liability insurance policy. It likely excludes mold treatment. If you are telling a customer you are getting rid of the mold and they put in a claim against you, you are screwed. If you treat mold, you need a pollution liability policy and some mitigation training (and depending on the state, probably some licensing). Those policies are expensive. Really expensive. Ludicrously expensive. “Great god almighty” expensive. I know, I pay the bill. It is also why mitigation contractors charge what they do.

As a a power washing contractor, you take care of dirt and algae, not the M word.

Here are a few before & Afters from when I originally washed the house… maybe this will give u a better idea of what’s going on. We have also had a record amount of rainfall since oct. In this area. Thinking that may have had a lot to do with this resurfacing so fast with all the moisture the past few months. Thanks for all the above information. Much appreciated!!!

Without doing testing, that looks like Cladosprorium. Material was probably went and the mold is growing through. At this point, it is going to either be a strip/mitigate/repaint…or hit with fungicide, top of the line exterior mold resistant paint and hope. I’d suggest getting a calibrated moisture meter into that wood to make sure it is not wet from inside from a ventilation issue. Painter probably also has some liability if they painted it wet and didn’t check the material moisture.

Thank you PeakofPefection.

I am curious though, why you say “This is why there is no EPA registration number on a bottle of bleach as a fungicide and it is not recognized as a fungicide and is not used for anything other than stain removal in the mitigation industry”

Isn’t chlorine used in pools, water supplies and many other situations for the purpose of killing germs, regardless of what the EPA says?

Good stuff.


Steven Leipzig
The Pressure King
Nashville, TN
Roof Cleaning - House Washing - Concrete Restoration
Residential and Commercial
ThePressureKing.com


Sorry…missed yiur reply. Bleach is commonly used as a BIOCIDE and is effective at this use. But it is not effective as a FUNGICIDE to treat surfaces in which the mold has grown into the surface. This is well known in the mitigation industry and why there is no EPA registration for fungicide use on a bottle of Chlorox.

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