Mold results are back...however??

Did a mold inspection Sunday 3/11
2 air-o-cell samples outside/ RH 23 / temp 67
1 air-o-cell sample in kids room/ RH 40/ temp 73
2 swab samples in the basement, on the block wall and on a wood floor joist/ RH 50/ temp 64

Results from the lab 3/16:
inside and outside air samples almost the same with no issues
swab sample on the basement wall was rare to low
swab sample in the basement floor joist high/ Aspergillus/Penicillium

The problem I’m having is not being able to determaine the cause of the high level in the basement floor joist and subfloor.

No rain 5 days prior to sampling.
No past or present water intrusion visible in the basement.
Exterior gutter/downspouts appeared functional.
Roof in bad condition, but no water intrutions visible in the attic.
Chimney in bad condition with no flashing, water intrutions noted in the attic. — the chimney goes straight down to the basement…(possible cause)

Let me know if there is any additional information needed to help me diagnose the cause.


Probably an unconditioned space and the wood has a high moisture content in the humid summer months.

No subfloor? Can’t tell in pic. Doesn’t look like it. What’s above that joist? Kitchen? Bathroom? (hint-hint). As Joe indicated, Indiana’s humid summers can get like a rainforest (like here in Minnesota) down there. If only that single joist with the issue, look above for kids splashing in the bath tub, leaking waterline to icemaker in refer, etc… No subfloor under that hardwood will cause it lo leak through without spreading out.

Maybe - Joe
Correct - Jeff - no subfloor - bare hardwood floor ( I stated subfloor meaning underneath or bottom side of floor)

All the (underneath) side of the floor has this mold, along with all the floor joist. I just took the one sample in the middle of the basement because it all appeared identical. The living room was above that particular area.

The client’s children have been ill for about 6 months and the doctors have no ideas. The client considered it may be from mold. Which he cleaned and sealed the kids bedroom closet and the basement. Cleaned with diluted water and bleach and sealed the baseboard trim with ---- you’ll love this one — a can of black spray sealant…the one that has a commercial on tv of how they spray a screen door and use it for the bottom of a boat…so the origanal mold growth had been unprofessionaly cleaned, then grew back by the time I arrived.

I checked all the water lines and drains thoroughly for any defect that may be causing the mold growth.
I even thought maybe condensation from the uninsulated duct work and/or plumbing, but there was a heat register for the basement.

I did (verbally) recommend a dehumidyfier for the basement, but so far thats all I’ve got.

I have yet to send in my written report until I can reasonably direct the client to the best possible cause of this mold.

Two legitimate suggestions so far…thanks…

What was the moisture content in the basement wood?

I never do more than one outdoor sample. I do 2 indoors and one outdoors. It would have been good to do an indoor sample of the basement air.

If the issue is with the entire floor and not on the walls of concrete floor(I’m assuming) then the issue would have to be with a high humidity level in the basement. What is being used in the home for heat? Boiler or Furnace? If it is a boiler then it could be caused from heat and humidity riseing and condensating on the cooler floor above. If it is a high efficent furnace then the same issue could present itself but less likely.Just a thought.

I often wondered about just one outdoor sample…guess I was just following proceedures.

moisture in wood joist varied from 10 to 12%

You assumed correctly.
Gas furnace.
and a good thought.

HMMMMMMM Ok so your saying that the moisture content was within normal values but mold is found underneath the entire floor. This sounds like a previous moisture issue or one that comes and goes and you were there during the goes period. During your interview with your client did he reveal any information about issues with the home besides the ones you already talked about. For mold to grow and flourish a moisture level of 17% or greater is required. Do you take relative humidity reading by chance? I believe I have more questions than answers at this point. Sorry:roll:

Any holes in the exterior rim joist? I had a client with a similar issue but it was on the wall as well. There were 4 1" holes in the rim joist that were allowing a small amount os snow in. The snow would turn to water and then get circulated through the basement causing a high humidity. In the spring, summer and fall the basement was dry but the problem would come back every year. People smarter then me figured this out as I had no clue except that i did point out the holes and took samples. I recommended further review by a mold remediation company and the gentleman that came to look at it had around 30 years expeirance on me. He figured it out in about two minutes. These are just thoughts and maybe provoke an answer from you or someone else.

RH = 50 in the basement

Ok…I think I have the answer…
I just spoke with the client and he (just now) informs me that last summer and this winter allot of dampness was accuring on the basement heating/ac ducts, and that after he cleaned up the mold he insulated the pipes which stopped the dripping from the pipes.

I specifically recall asking him at least twice if he had ever noticed condensation on any of the pipes in the basement or throught the home, which he answered no, each time…

I enjoy working on a puzzle, but get a little frustrated when I find that not all the pieces are there…

Unless someone does not agree with this, I will be confident in calling the past condensation as the cause.

I appreciate all your help in troubleshooting this…

Ding ding ding ding ding, We have a winner. :mrgreen:

…blah, blah, blah… **indicators are **…blah, blah, blah… **most likely a result of **… blah, blah, blah…

Unless you are absolutely certain… NEVER claim that something is a result of something else.

I completely agree Jeff

Care to elaborate more?
I understand your deduction, but can you add more to the evaluation?


I agree with others that quoting the exact cause of mold is not a good idea. The only statement I make is mold is a moisture related problem. There are many sources of water & humidity in a basement or crawlspace. I would stick with the “most likely” phrase or list some of the more typical sources of moisture.

I’m seeing the topic being swayed from finding the cause to defining the cause to the client.

Finding the cause is essential for me and beneficial in my explanation to the client. That was the initial question.

I most certainly appreciate the input on the wording, but I have yet to set in stone any verbiage that will be on my client report.

From one mold inspector to another I’m trying to establish a viable cause or causes. Which, again I believe to be the condensation, unless somebody else has another possible cause.

Hi Randy
Would you care to make a comment on the cause?