View Full Version : White mold in crawl space.

03-26-2008, 12:00 PM
Inspected a house yesterday built in 1945. As you can see by the pictures, there was white mold in various places in the crawl space. What is perplexing is that it is only on the plywood not the joists. It is a dry mold. The crawl space was extremely dry to the point that the soil was like powder. There was not a vapor barrier and it had good ventilation but it appeared that the mold was forming near the ventilation vents. I am thinking that this mold is dry because of the winter climate and reactivates itself once it gets hot and the humidity levels rise.

I need help in identifing the problem as well as why it is not on the joists.



Joe Griffin
03-26-2008, 12:33 PM
Hi Jim. I am no mold specialist, nor do I play one on TV. So with that being said, unless my Air Quality Specialist, (Industrial Hygienist) identifies it as such, I would refer to this as a "fungus or "mold-like" substance.

I have seen a lot of "possibly mold" covered surfaces in my day, this is a different surface effect than normal, no visible spore-like formations, fur, growths, etc. It seems to be worse at the butt end joints? Where water may have seeped in and dried? It has that efflourescence look to it. May be time to call in a specialist to determine if this is indeed a harmful mold. Unless you are a qualified, certified mold inspector that is. If you are, I defer.

Raymond Wand
03-26-2008, 01:39 PM
I am not sure its mould either, and in this case you would have to collect a sample and send it in for analyzes.

It could also be paint/white wash from salvaged plywood.

03-26-2008, 02:06 PM
It is definately mold of some type. If you look at the nails protruding through, they are rusty from moisture.

Joe Griffin
03-26-2008, 02:58 PM
Jim, I see rusty nails every day in basements, crawl spaces, attics with no accompanying mold-like substances. Is there humidity and water vapor condensating? You betcha. Just because nearby metal has some surface rust, it is a bit of a leap to call out "mold". Even though you may be right, be prepared to answer questions if it isn't.

I refrain from trying to label hazardous materials such as asbestos, mold, lead paint etc. in my reports. I will look for these things and I am damn good at finding them, but I don't have a mobile lab at hand to accurately identify them without a doubt.

So, I provide a detailed photo, and point out that due to the genre, location, appearance, it may be one of these above named substances.
And I provide links to the EPA website which applies. They can take it from there.

Now if you happen to be one of the many inspectors who are licensed, schooled, and insured enough to make these calls with complete confidence, have at it.

I am of the ilk that it is best to do one thing very well, and not a lot of things not as well. We gave up septic inspections for that reason.

Ron Bibler
03-26-2008, 03:51 PM
I see this kind on mass in Calif. all the time. I put this statement in my reports. and move on.
Finding The inspector noted condition of an unknown fungi/mold located on section of the sub-structure framing. The owner/buyer should read the statement below for more information.
"This property was not inspected for the presence or absence of health related molds or fungi. by California law we are neither qualified, authorized or licensed to inspect for health related molds or fungi. If interested parties desire any information about the presence or absence of health related molds or fungi you should contact an industrial hygienist for further inspection."
****** Further Inspections Recommended ******


Paul Kondzich
03-26-2008, 08:11 PM
Jim, what Joe is saying I think is that we as home inspectors should not say the "mold" word. Unless of course you are an industrial hygentist. And then say it is "definetly mold " is ever worse.

Jack Feldmann
03-27-2008, 04:05 PM
I disagree that we as home inspectors should stay clear of using words like fungus or mold.

Most everyone knows what mold looks like. I would find it very hard to believe that anyone over the age of 10 has not seen at one time or another, some food that was left in the refrigerator way too long and started growing that fuzzy stuff on top. We all now what it is. We may not know what kind of mold it is, or if it is harmful - but we do know it is mold.

The dictionary uses mold and fungus to define each other.

I see nothing wrong with calling out something that looks like mold/fungus in my report. I'm not telling them WHAT kind it is, or if it is harmful - just that it's there.

I once got a call from a pissed off seller. He said I had called out fungus in his basement (I even took a photo). He said "Did you test it?"- "no".- "How do you know it's mold?" - "Because I know what it looks like". After a couple minutes I asked him, "You ever see fuzzy stuff on chesse in your refrigerator?" - "Yes"

"What is it?" - "Mold" - "How do you know if you didn't test it?" He then hung up the phone.

Just my opinion

Billy Stephens
03-27-2008, 05:02 PM
I wonder how much Voltage is running through the open Electrical Box.

Michael P. O'Handley
03-28-2008, 03:45 AM

It looks like the start of some brown rot fungi. No need to start freaking out about some fungi in the crawlspace; there's no way the owners will get exposed to it unless the interior of the home is open to the crawl someplace so spore can spread up into the house.

Write it up and recommend they get the underside of the floors treated with some BoraCare. BoraCare is a glycerin-borate mix. You cut it 1/1 with water and apply it with a pump sprayer. It's toxic to all forms of fungi but non-toxic to humans, and it will soak into the wood making it immune to future fungal growth.

Powder-like or not, that soil is giving off moisture - about 11 gallons every 24 hours for every 1,000 square feet. Get the soil covered with a cap sheet after the underside of the floor is treated.



Raymond Wand
03-28-2008, 04:00 AM
Strange the white substance is not on the joists if its mould. Is the plywood prone to mould because of the glues?


Jerry Peck
03-28-2008, 07:27 AM

As Mike says, cover the crawlspace with a moisture barrier.

As far as cleaning it, I would probably lean toward using a bleach/water mix, with proper precautions when applying it with a pump up sprayer.

Regardless what is used to 'clean it', doing so will be done in a confined space without adequate ventilation - so care much be taken.

I would not recommend in writing what to 'clean it with', only that it should be 'cleaned'. Most types of fungi will attack wood (they dine on the cellulose in the wood), some damaging the wood faster than others.

Probably not a 'big deal' regarding mold, however, over time, it could become a 'big deal' regarding the plywood and its replacement (which would be a 'VERY BIG DEAL').

CaoimhĂ­n P. Connell
04-03-2008, 05:05 AM
Good morning, Jim

I looked through your photos, and although the photos don’t really provide sufficient information to conclusively rule in or rule out whether the material is mould, they do provide a wealth of information, and my take on it is a little different.

1) The white material was on the boards when the boards were installed during construction.

2) If the material is mould, no growth has occurred after construction.

3) Cleaning of ANY kind would not be recommended.

4) I would definitely not recommend the application of bleach.

5) Obviously the area of “contamination” has not changed since the time of construction, and therefore the situation is stable.

Caoimhín P. Connell
Forensic Industrial Hygienist
Forensic Industrial Hygiene (http://www.forensic-applications.com)

(The opinions expressed here are exclusively my personal opinions and do not necessarily reflect my professional opinion, opinion of my employer, agency, peers, or professional affiliates. The above post is for information only and does not reflect professional advice and is not intended to supercede the professional advice of others.)


Cliff Miller
07-17-2008, 09:46 AM
While I'm not a building inspector, I have worked occasionally with FEMA and other government agencies and would like to mention some good resources regarding mold. The following URLs can be helpful:

FEMA: Removing Mold from Your Home (http://www.fema.gov/rebuild/recover/mold.shtm)

A Brief Guide to Mold, Moisture, and Your Home | Mold | Indoor Air Quality | Air | US EPA (http://www.epa.gov/mold/moldguide.html)

CDC Natural Disasters | Mold After a Disaster (http://www.bt.cdc.gov/disasters/mold/)

CDC Mold | Protect Yourself from Mold (http://www.bt.cdc.gov/disasters/mold/protect.asp)

I've also uploaded a couple of documents, although I was not able to upload all that I wished. One, the EPA guide entitled "Mold Web Course" or moldcourse.pdf, is too large for this forum (5.45 Megs). Another is one I complied from online (html) pages and is in MS Word (doc) format and is not compatible with the upload-acceptable formats here (jpg, PDF, gif, etc.). Perhaps MS Word files could be added to those formats which can be uploaded. In the meantime, the info is available online from the sources cited above. Also, don't forget to wear an N-95 respirator or equivalent if you are trying to remediate mold or even inspecting a large amount of it close up.

Glenn Stewart
09-13-2009, 02:46 PM
Looks like recycled lumber to me, where the boards and panels have gone through a large drum sander... leaving behind white paint in the pores and grooves of the wood.

Eric Barker
09-13-2009, 04:07 PM
There are many many species of fungi, a majority of which have yet to be identified. They all have their particular tastes for food. Some may like plywood while others prefer dimensional lumber etc.

Also, using bleach is not recommended - especially with a sprayer. Bleach for one thing is a disinfectant, not a cleaner. Second, a sprayer will aerosolize the bleach for more readily inhalation.

Finally, mold is like asbestos. You may have a very good idea of what it may be but until it is tested you could not authoritatively say so without the recognized confirmation - proper evaluation does not involve opinion.

Glenn Stewart
09-13-2009, 06:11 PM
Eric... I'm 100% in sync with your comments about having a suspected bio-organic growth evaluated/tested by an Industrial Hygenist or other qualified personnel.

Ted Menelly
09-13-2009, 06:52 PM

White mold, brown mold , I see it all the time. Treat with a borate product like timbor and it will not come back. White mold and brown mold are not soft to begin with but if left UNTREATED it will rot the would and then of course it will be soft.

I may not be an expert but I have seen it and treated it all my life. Borate product of one manufacturer or another. It helps greatly if the areas are hit with a wire brush first and then sprayed. I cannot tell you how many times I have inspected and then had treated afterward and problem solved and not returned. Sounds like plenty of ventilation but I would also advise that the duct work and vent openings be removed from the crawl. Air leakage is causing instability in the crawl. A slow warming up or cooling down along with humid air is not bad. Rapid cooling in some areas or just the cool duct work reaks havoc in crawl. Especially the duct connections at the supply vent at the floor. It is going to be colder there even if there is not air leakage and condensing of the moisture in those areas at the plywood or 1x sub floor.

Sprayhing bleach over head in a tight crawl...not cool. Use a timbor or such.

09-14-2009, 11:17 AM
See this in crawls often. It is usually accompanied with a brown type of wood fungus / residue. It is a little hard to tell form the picture but This is most likely a wood eating fungus. When the wood maintains above a 28% moisture content this fungus may set in. It is the precursur to dry rot - which is actually caused by wet rot. If left untreated and/or the conditions causing it are not corrected it can do extensive damage. I see more damage from this type of wood fungus than termites and I am in a heavy termite area. A borate solution will kill the fungus, but the fungus will possibly attack other areas if the moisture conditions are not corrected.

Hope this helps - Tom

Cobra Cook
09-14-2009, 08:52 PM
Have someone certified in mold testing to take a swab sample and an air sample both under the house and outside to determine if what you believe to be mold is mold and wheither it is living or not. Makes a big difference. Mold under the house can and will eventually enter the house through the natural venting process. From the pictures it does not appear to be living but only testing in a certified lab can tell you that. Bleach will only kill on the surface but does not enter the wood where the fungi are eating away the wood from the inside. They are like a jelly fish tinacles, that is what needs to die. I use Easy Decon 200 the same stuff the military uses to kill germs u never heard of, epa approved and will kill every thing, pest,termites rooches even u if u enter without a full face mask with the proper filters while u are fogging. After it dries it is non toxic and simply cleaned with water or vacuumed with a good filter. under the house cover it with a vapor barrier and don't worry it is dead. I charge 75 dollars per sample and to fog an average sized home 300 dollars with proven results. Moral to the story don't scare the owner or buyers if you are not sure. Looks like mold, looks like asbestos. Do you eat mushrooms, do they look like mold?

Eric Barker
09-15-2009, 06:36 AM
I don't believe that you will find any standard that advises leaving dead mold. It must be removed and what can't be should be encapsulated. Remediation often involves separating contaminated areas from non with regulated pressure differentiation. Finally, a "good filter" is also not found in any current standard. It must be a HEPA filter.

On HEPAs - a recent study has found that a large percentage of HEPA filter vacs don't do the job that they're listed for. This is often due to poor fittings/seals around the filters themselves.

Cobra Cook
09-15-2009, 11:52 AM
The mold under the house which will be dead mold will be encapsulated when you put the vapor barrier ie: plastic at least 4 mil thick which should be sealed around the parameter. What do you propose, remove all of the dirt from under the house? When I fog a house with easy decon the entire house is fogged due to the fact that if mold or bacteria is in the entire house or building through the movement of air through the ventilation system. The minute microbes are floating in the air and crevices and when ED200 comes in contact, lights are out. If you do not control the reason the microbes took up residence it will eventually come back. As far as vacuums, when i said a good, i ment a hepa filter should be used. Some work better than others. While some of the chemicals used can kill some of them ED200 also turns them from a toxic waste to an non toxic waste which can be disposed in any land fill.