New page on mould sampling myths

[Chris Bernhardt]

Concerning Jerry's photo I have followed enough new construction to their one year warranty inspections to know that the decking could have been installed in pristine looking condition and then develop the type of moldy appearance in Jerry's photo. I would bet my lunch that the mold in Jerry's case developed post construction.

That the mold patterns change at the boundaries of the plywood panels is nothing but what I would expect. The panels vary in their density and degree of surface damage from the milling process. OSB panels on the other hand are much more consistent in density and surface damage and often present an even distribution of mold development across panel boundaries.

From prior discussions it was my understanding that mold just doesn't have the power to break down undamaged cellulose, and that one of the main reasons mold infects the surfaces of OSB & plywood more readily then lumber is due to the degree of surface damage that exists as a result of the milling process. But in addition to that I also think that form and temperature significantly play a role in why the framing is the last to get infected.

Correct me if I wrong, but in theory if one could cut/mill at a molecular level cleanly, there would be no compromised cellulose chains for mold to break down.

That a spot of growth apparently spans from one side of a rafter to another again is not an indication that the growth took place before the panel was installed. I know this because I have seen enough decking before at the new home inspection and a year later at the warranty inspection to conclude differently. There are other plausible reasons for the growth to span across framing members (decking not full contact with the framing member for one, but I think it has more to do with the physical characteristics that exist in that area of the panel).

One cannot reasonably come to a conclusion by looking at a photo what the moisture conditions are in an attic little alone if the mold is active or inactive. I know this because I routinely sample vapor pressure levels, probe & scan framing and decking with several different types of moisture meters and scan attics with IR, particularly suspect attics with moisture stains, moisture darkened decking and mold in the homes that I inspect with often surprising results.

In Jerry's case I would conclude that after trying to get a reasonable indication of the moisture content of the decking, that indicates it's say below at least 16% and that the vapor pressure levels measured at the roof decking are on par with those on the exterior, that whatever was the source of the moisture is now not only gone but not even in the proximity, although I would try and figure out what it originally was. I can't think of any reason why anyone could justify removing the appearance of the mold in Jerry's case.

In Bain's case that sure looks like bulk leakage and not condensation to me.

Chris, Oregon

[Chris Bernhardt]

Caoimhín,

Is Concrobium snake oil?

I have been recommending the stuff a lot as of late; haven't heard that it doesn't work.

Chris, Oregon

[Jerry Simon]

By nature, mould (why is it spelled with a "U" now?)

Apparently, every english-speaking country, save for the USA, spells it that way.

Jerry, sometimes it takes a very special person to appreciate your comments!

Hi Les...

I was serious, and I believe correct about that. Not sure what you mean...

[Les]

Jerry, I was remarking about the "save for the USA", part of your comment. I believe your comment to be 100% correct.

I thought you had "participated" in Bonnie's discussion regarding using save. Click on over there.

[Jerry Simon]

Jerry, I was remarking about the "save for the USA", part of your comment. I believe your comment to be 100% correct.

I thought you had "participated" in Bonnie's discussion regarding using save. Click on over there.

Now I got ya. You know, I read that post, and it didn't stick with me. I still think "save for" sounds okey-dokey. "Except for" might have worked better.

Thanks for trying to give me credit, though, for thinking I was smart enough to play with the posts like that.

[Les]

Chris,

I am not CPC, but have some years of experience with Concrobium. My experience and opinion are mine alone and not based on any science. We use a couple hundred gallons per year, typically after a tear out and clean up. I have no confidence in the product and don't know if it works or not. It is non-toxic, easy to use and customers want it. It is expensive to use. You must carefully read label directions and understand what it is purporting to do.

How do we know it works when it is to be used after a cleaning and mold removal? Re-visiting a job after a year with and without application has shown no difference, in our experience. I don't think it hurt anything. There are dozens of other products that claim to do everything that simply do not do anything. Many insurance jobs specify a "mold control agent" = concrobium.

I confess that I do read everything I can about mold and try to apply that disparate info in several activities this company does: Inspections, pest control, restoration, litigation, site work. I remain of the belief that mold, as a stand-alone issue, is best dealt with by acknowledged experts. Inspectors can and should act only as a type of bridge between client and issue. We do NO mold testing. We do quite alot of investigation about how it got started and why - building science.

Wheather or not CPC is a "final" authority is not important to us. He produces information that usually is well thought out and logical and that causes us to think.

[Caoimhín P. Connell]

Hi Chris!

Remember, we can’t take this too serious and don’t forget how I prefaced my answer:

Now – for fun, here’s what I would say about the staining (based on nothing more than the photo):

And that I did. No one except John B knows the conditions in the attic. But even if John said the attic contained four inches free standing water, my comments would still have been the same, since there is no evidence of a water problem in the photo. Whether the attic in question has, or has not, a moisture problem is not what I am discussing. I am merely discussing what does the photo say. I stated there is nothing in the photo that suggests a moisture problem, and then I gave the rationale to support the argument.

You say:

I would bet my lunch that the mold in Jerry's case developed post construction.

Maybe so … but there is nothing in the photo that supports the argument. Or is there? And if so, please explain. It is possible that the photo contains support for many differing hypotheses – but explain what evidence in the photo supports your argument.

Cellulose:

I’m not sure where you heard that mould cannot degrade wood except due to the mechanical action of a saw or plane. The issue of wood degradation is not exclusively a question of cellulose degradation. Cellulose degradation is not exclusively at stake, since the matrix of wood involves lignin, xylans, hemicelluloses, pectins, and other kinds of long chained molecules that confer structural integrity and other properties (including aesthetic) to the wood.

I certainly agree with the concept that a saw or any other mechanical device disturbing the wood matrix would increase the surface area or create breaks in the structure (thus increasing potentially habitable environments) and would also disrupt the natural intertwining of lignin and cellulose. But it would not be incorrect to state that left undisturbed by machining or mechanical action, mould would be incapable of degrading wood in general and cellulose in particular.

Wood and plants are essentially made of sugar, and to a lesser extent, phenolic polymers. Cellulose is essentially a long series of cyclic glucose sugar molecules strung along like beads on a chain; the beads are the individual glucose molecules and the chain is where the individual glucoses have attached to each other, not unlike the coupling of cars in a train.

Many moulds have the ability to degrade the glucose bonds, at specific locations and begin to break off glucose chunks. By mechanically disturbing the wood, one merely provides more opportunity for hospitable sites of degradation. But the degradation is not incumbent exclusively on the mechanical actions of the lumber mill, carpenter, or woodworker.

For a start, the matrix of wood, while ordered, is also chaotic, and within the microfibril bundles of cellulosic chains there are random “loose-endsâ€

[kurt]

I got your "in the photo" analysis just fine. Not sure why folks kneejerked elsewhere.

And, I agree with Les'. I don't consider this to be biblical truth stuff; I find it to be a worthy counterpoint to the mounds of crap we confront on a daily basis. I can sift through it and find reality, unlike the sales pitches we're bombarded with.

Also, the idea that mold doesn't degrade wood is a surprise to the old growth forests that are regenerated by molds and fungi breaking down old fallen wood (at least, the tiny bit of old growth still left standing!).

That part's true, isn't it?

[Caoimhín P. Connell]

Good morning, Kurt-

You point is well taken and was also noted about 100 years ago:

Decomposition of wood is an important part of the carbon cycle of nature. Decomposition is caused by fungi, insects, and marine borers that use the wood as food or shelter, or both. Lignin in wood provides a physical barrier to enzymatic decomposition of cellulose and hemicelluloses. This barrier is breached mechanically by insects and marine borers, biochemically by white- and soft-rot fungi, and possibly by small nonenzyme catalysts in the case of brown-rot fungi. Cellulose is degraded by endo- and exo-glucanases and b-glucosidases, hemicelluloses by endo-glycanases and glycosidases, lignin by nonspecific enzymes, and perhaps by nonenzymatic, oxidative agents. Rapid strength loss occurs with all decay fungi; but especially with brown-rot fungi. Strength loss due to insect attack is roughly proportional to the amount of wood removed. Fungal decomposition of wood can be prevented by keeping it below its fiber-saturation moisture content (approximately 27% of its dry weight) and by using the heartwood of naturally durable woods (species) or preservative- treated wood. Useful application of wood-decomposing fungi is limited currently to production of edible mushrooms. Potential applications include biological pulping, pretreatment for enzymatic conversion of wood to sugars, and waste treatment. Many aspects of wood biodecomposition have not been researched adequately. Millions of tons of wood are produced every year in the forests of the world. Observation, however, tells us that the sum-total of wood upon the surface of the earth remains fairly constant from year to year and from century to century. We must, therefore, conclude that there are destructive agencies at work by which millions of tons of wood are destroyed annually. Regarded in this light the problem of what these destructive agencies are, and how they act, becomes of general scientific and economic interest.

A. H. R. Buller, (Econ Biol. 906 (1) 101)

Cheers -

CPC

[Chris Bernhardt]

I got your "in the photo" analysis just fine. Not sure why folks kneejerked elsewhere.

I figured it was a EW call, but wanted to poke my foot in it. That's why if any EW stuff comes up I tell em to call Jim Katen. Don't put me up there or I will be spending the next month trying to get both my feet out of my mouth; it may even take surgery.

I’m not sure where you heard that mould cannot degrade wood except due to the mechanical action of a saw or plane. The issue of wood degradation is not exclusively a question of cellulose degradation. Cellulose degradation is not exclusively at stake, since the matrix of wood involves lignin, xylans, hemicelluloses, pectins, and other kinds of long chained molecules that confer structural integrity and other properties (including aesthetic) to the wood.

I read it somewhere, that while decay fungi could snip away, that mold could not as easy breakdown wood past the surface. Based on this and past discussions I was theorizing that if you could mfg plywood or OSB without tearing the surfaces as much that they would be less susceptable to colonization like the trusses are.

However, I do know this – if it is being prescribed as a necessary element of a mould remediation process by a mould remediators, then the mould remediator is selling snake oil, even if the product called Concrobium is very effective at what it claims to be able to do.

I didn't know, but suspected that was the truth of it.

Chris, Oregon

[Bain]

Originally posted by Caoimhín P. Connell

And that I did. No one except John B knows the conditions in the attic. But even if John said the attic contained four inches free standing water, my comments would still have been the same, since there is no evidence of a water problem in the photo. Whether the attic in question has, or has not, a moisture problem is not what I am discussing. I am merely discussing what does the photo say. I stated there is nothing in the photo that suggests a moisture problem, and then I gave the rationale to support the argument.

Caoimhin,

I'm not qualified to even discuss this stuff with you, much less get into a debate about it. The only thing I have to offer is real-time experience. The house the photos came from--and I think you meant "crawlspace" rather than "attic"--contained an almost overwhelming dank, musky odor that most of us associate with moisture problems. When I left the house, my respiratory system was screaming and I had a horrible headache. The crawlspace itself? Wicked damp to a degree that my knees and hands sunk into the ground a couple of inches as I negotiated my way through it. Point being, to a home inspector dude, all of the foregoing indicates a moisture problem. And then I saw the black gunk on the foundation. Maybe it wasn't mold in a biological sense, but it also wasn't a moisture stain or mere dirt. I wasn't being flippant when I asked you what it was. I truly want to know. There's nothing inorganic I've ever seen that would create stains like that--and it was somehow related to whatever was going on within the floor system.

( I screwed up the quotes. This is Caoimhin)

You say:

I would bet my lunch that the mold in Jerry's case developed post construction.

Maybe so … but there is nothing in the photo that supports the argument. Or is there? And if so, please explain. It is possible that the photo contains support for many differing hypotheses – but explain what evidence in the photo supports your argument.

(End Quote)

This has nothing to do with the photo. Real time experience suggests that OSB would never lie around a construction site long enough to develop that degree of mold/water-stains/whatever. We've all looked at tons of new construction, and I doubt anyone's ever seen that kind of decking in a freshly-constructed house. Therefore, logic suggests that the stains occurred post-construction.

I, too, understand what you mean by in the photo but for those of us who have to look at this stuff and try to explain it to our clients, knowing what call to make can prove difficult. We can punt, of course, but like you've said, most of the schmucks running around calling themselves mold experts don't know a damn thing about what they're talking about. We can revisit my crawlspace photos as an example. Say Chad broke an ankle and I'm checking out a house for his daughter. My initial impulse would be to tell her to run like a striped-ass ape. The last thing I'd want to tell her was that I didn't see any signs of moisture problems.

[Caoimhín P. Connell]

Hi John!

I'm an idiot! Now that I've confused everyone… we were discussing Jerry Simon's attic photo and your crawler photos, but in my response to Chris, I accidently referred to your name when I mentioned Jerry's attic photos. Sorry for the confusion.

I did address your crawler photos in post #13 of this thread. As to what it is … I dunno. But, as I said in the post, it isn’t mould. Now having said that, if the block walls are painted and the paint contains a starch, then it could be mould (but it could also be the leach field backing up…) Also, when I was a chisler in Ireland, we could by cinderblocks that were made with straw mixed in; mould could grow on those.

Might be just about anything from a lichen to a water stain. In this case, without actually being there, it’s easier to say what it isn’t rather than what it is. Hard to tell from a photo. Dunno. And since you’re in KY, it’s not likely anyone will pay may out there to look at it!

Cheers!

Caoimhín P. Connell

Forensic Industrial Hygienist

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.)

AMDG

[hausdok]

John,

Is it possible that all of that staining is along the wall directly behind a concrete front porch and this is dirt and funk that's washed down behind the rim and onto the walls?

OT - OF!!!

M.

[Bain]

John,

Is it possible that all of that staining is along the wall directly behind a concrete front porch and this is dirt and funk that's washed down behind the rim and onto the walls?

OT - OF!!!

M.

No, the gunk was all over the place, oozing down the foundation. The first photo is a shot of the front foundation wall, while the last three are of the rear of the house.

[Jim Katen]

. . . Also, the idea that mold doesn't degrade wood is a surprise to the old growth forests that are regenerated by molds and fungi breaking down old fallen wood (at least, the tiny bit of old growth still left standing!).

That part's true, isn't it?

The experts that I've read and talked to all tell me that the fungi that we call mold can't break down the cell walls of trees and can only cause limited damage to the surface of a piece of lumber. I think that the wood-rot fungi are the ones that are breaking down the old fallen wood in forests. (Along with insects and bacteria.)

- Jim Katen, Oregon

[Jim Katen]

Good morning, Kurt-

You point is well taken and was also noted about 100 years ago:

Decomposition of wood is an important part of the carbon cycle of nature. Decomposition is caused by fungi, insects, and marine borers that use the wood as food or shelter, or both. Lignin in wood provides a physical barrier to enzymatic decomposition of cellulose and hemicelluloses. This barrier is breached mechanically by insects and marine borers, biochemically by white- and soft-rot fungi, and possibly by small nonenzyme catalysts in the case of brown-rot fungi. Cellulose is degraded by endo- and exo-glucanases and b-glucosidases, hemicelluloses by endo-glycanases and glycosidases, lignin by nonspecific enzymes, and perhaps by nonenzymatic, oxidative agents. Rapid strength loss occurs with all decay fungi; but especially with brown-rot fungi. Strength loss due to insect attack is roughly proportional to the amount of wood removed. Fungal decomposition of wood can be prevented by keeping it below its fiber-saturation moisture content (approximately 27% of its dry weight) and by using the heartwood of naturally durable woods (species) or preservative- treated wood. Useful application of wood-decomposing fungi is limited currently to production of edible mushrooms. Potential applications include biological pulping, pretreatment for enzymatic conversion of wood to sugars, and waste treatment. Many aspects of wood biodecomposition have not been researched adequately. Millions of tons of wood are produced every year in the forests of the world. Observation, however, tells us that the sum-total of wood upon the surface of the earth remains fairly constant from year to year and from century to century. We must, therefore, conclude that there are destructive agencies at work by which millions of tons of wood are destroyed annually. Regarded in this light the problem of what these destructive agencies are, and how they act, becomes of general scientific and economic interest.

A. H. R. Buller, (Econ Biol. 906 (1) 101)

Cheers -

CPC

Buller's talking about wood-rot fungi, not mold.

If the fungi that we commonly refer to as "mold" can deconstruct wood, I'd love to hear about it. Everything I've learned to date tells me otherwise.

- Jim Katen, Oregon

[Caoimhín P. Connell]

Hello Jim –

Although Buller is speaking of other fungi, moulds are capable of degrading cellulose and the other complex entities in plant material and wood. I think the confusion may arise from a distinction between what a mould can do, and what are the practical implications of what the mould has done. Several moulds have the distinct capability of breaking down cellulose and other complex entities in wood and other plants.

However, the practical implications is that since the process is slow, and the degradation is mostly superficial, the practical upshot is that it is of little importance from a structural integrity point of view.

An excellent discussion of the subject is found in a paper titled Aspergillus Enzymes Involved in Degradation of Plant Cell Wall Polysaccharides (Devries RP, Visser, JA), Microbiology And Molecular Biology Reviews, Dec.2001, p.497–522.

Regarding this genus of mould, the authors state:

Four classes of enzymes are involved in the biodegradation of cellulose. Endoglucanases hydrolyze cellulose to glucooligosaccharides. Cellobiohydrolases release cellobiose from crystalline cellulose. Glucosidases degrade the oligosaccharides to glucose. Exoglucanases release glucose from cellulose and glucooligosaccharides. The distinction between exoglucanases and cellobiohydrolases is not always clear due to differences in the methods used to study these enzymes. All four classes of enzymes have been identified in the aspergilli, although the number of isozymes produced by different species or even strains of the same species can differ. An analysis of the production of endoglucanases by 45 A. terreus isolates not only revealed different electrophoretic mobilities for the enzymes of the different isolates but also indicated the absence of endoglucanase I in a number of the isolates Endoglucanases and glucosidases are also able to degrade the backbone of xyloglucan. From A. aculeatus an endoglucanase has been purified that is specific for the substituted xyloglucan backbone.

Finally, it is also important to note that just because a specific genotype is capable of producing cellulolytic enzymes, does not mean that it necessarily must. We can say the same thing about various mycotoxins - just because a particular mould is capable of producing a specific mycotoxin, does not mean the presence of the organism is synonymous with the presence of the mycotoxin.

Cheers!

Caoimhín P. Connell

Forensic Industrial Hygienist

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.)

AMDG

[Jim Katen]

Hello Jim –

Although Buller is speaking of other fungi, moulds are capable of degrading cellulose and the other complex entities in plant material and wood. I think the confusion may arise from a distinction between what a mould can do, and what are the practical implications of what the mould has done. Several moulds have the distinct capability of breaking down cellulose and other complex entities in wood and other plants.

However, the practical implications is that since the process is slow, and the degradation is mostly superficial, the practical upshot is that it is of little importance from a structural integrity point of view.

An excellent discussion of the subject is found in a paper titled Aspergillus Enzymes Involved in Degradation of Plant Cell Wall Polysaccharides (Devries RP, Visser, JA), Microbiology And Molecular Biology Reviews, Dec.2001, p.497–522.

Regarding this genus of mould, the authors state:

Four classes of enzymes are involved in the biodegradation of cellulose. Endoglucanases hydrolyze cellulose to glucooligosaccharides. Cellobiohydrolases release cellobiose from crystalline cellulose. Glucosidases degrade the oligosaccharides to glucose. Exoglucanases release glucose from cellulose and glucooligosaccharides. The distinction between exoglucanases and cellobiohydrolases is not always clear due to differences in the methods used to study these enzymes. All four classes of enzymes have been identified in the aspergilli, although the number of isozymes produced by different species or even strains of the same species can differ. An analysis of the production of endoglucanases by 45 A. terreus isolates not only revealed different electrophoretic mobilities for the enzymes of the different isolates but also indicated the absence of endoglucanase I in a number of the isolates Endoglucanases and glucosidases are also able to degrade the backbone of xyloglucan. From A. aculeatus an endoglucanase has been purified that is specific for the substituted xyloglucan backbone.

As I read it, it sounds like he's saying that the aspergilli aren't able to break down cellulose without some help.

This is an important issue because, at least in my area, one justification that's presented for mold treatment is that, if left untreated, the mold will cause damage to the structure. In my experience, this isn't true. There are rot fungi that thrive under the same conditions as mold, and the rot fungi can certainly do a lot of damage to the structure, but, as far as the structure is concerned, mold seems to me to be fairly benign.

Finally, it is also important to note that just because a specific genotype is capable of producing cellulolytic enzymes, does not mean that it necessarily must. We can say the same thing about various mycotoxins - just because a particular mould is capable of producing a specific mycotoxin, does not mean the presence of the organism is synonymous with the presence of the mycotoxin.

My understanding is that it's biologically "expensive" for a mold to produce spores; it takes a lot of resources. The molds prefer no to expend resources unless necessary. When conditions are favorable, with good temperatures and a plentiful supply of food & water, the mold has no incentive to produce spores and, therefore, no reason to produce mycotoxins. When conditions start to degrade -- for instance when we stop the leak that's allowed the mold to grow and things start to dry out -- the mold reacts to the stress by producing spores that will survive the coming drought. It then invests the resources necessary to produce spores, release mycotoxins and release the spores. This is why we often find healthy, indeed thriving colonies of mold with no evidence of mycotoxins and no physical reactions from the people living amidst them. It's also why people's physical reactions sometimes worsen when we take measures to eliminate the source of the water that allowed the mold to grow in the first place -- the people are having allergic reactions to the sudden, massive increase in spores. (Not, as the media has claimed, as a toxic effect of the mycotoxins -- unless, of course, the people are eating the mold.)

Can something similar happen with enzyme production? If the mold finds itself running out of food, can it alter its enzyme profile to produce food from whole wood cells? If so, why don't we see this happening more often?

- Jim Katen, Oregon

[Caoimhín P. Connell]

Jim –

First let me say you have some excellent and penetrating questions. I started my response and then left to have my dinner, and so if there is a response in between I apologize for not addressing it.

Comment:

As I read it, it sounds like he's saying that the aspergilli aren't able to break down cellulose without some help.

Response:

As far as the Aspergilli needing “helpâ€

[John Dirks Jr]

This stuff was like little plumes growing on stalks. Not the white fuzzy stuff to the left, but to the right there is rows of tiny pale grayish stuff on stalks. The picture isn't the best. I should have gone out and gotten my good camera for this one.

Click to Enlarge

49.38 KB

[Caoimhín P. Connell]

Good morning, Gents:

In the past, human exposure and environmental assessment samples were collected and interpreted by professionals with proficiency in those fields following standardized sampling protocols and interpretation protocols. With the advent of the indoor mould craze, a plethora of instant mould experts started collecting samples using non-standard and meaningless protocols and mostly relied on insupportable interpretations.

Within the Home Inspection industry, we have mostly seen Home Inspectors relying on the laboratory to interpret their results – in spite of warnings from the EPA and the CDC that this is inappropriate. NACHI certified inspectors, especially, have announced with pride that they let ProLabs interpret their data (which has resulted in many grossly misinterpreted data and unsupported conclusions).

For approximately 10 years FACTs personnel have stated very clearly that the Laboratory is the LEAST capable entity for data interpretation. Yesterday, we received with interest the following circular from EMSL Analytical Inc., a laboratory involved in spore trap analysis and other type of indoor mould analysis:

Should You Trust a Laboratory to Interpret Your Mold Results?

Indoor air quality as a scientific discipline is evolving as our knowledge of the subject increases. We know that sample results for fungi and fungal spores are highly variable even under the most controlled sampling conditions. Given the complexity of interpreting your results, can you really rely on a lab doing this for you?

Here are some reasons not to:

1. Laboratory results by themselves should not be used alone to form the basis of your data interpretation. Visual inspection of the site, site location and nearby land use, understanding the site history, identifying indoor micro-climates, and interviews with affected occupants should play a major role in your result interpretation.

2. Fungal counts have spatial, geographic, local land use, seasonal and diurnal variability just to name a few. This variability can be orders of magnitude different in samples that are taken a few minutes apart! An interpretation of your samples that is based on subjective, un-validated internal criteria developed by a laboratory is a great way to make incorrect conclusions!

3. We know that different sampling devices result in different collection efficiencies that depend on the spore size. This variation is significant when comparing sampling devices. These collection efficiency differences are not taken into account by labs offering this type of data interpretation! What are you really getting? The sole purpose of a laboratory is to provide you with independent, objective, and scientifically defensible data.

Labs that offer you “statistical data interpretationâ€