MOLD AGE, HOW OLD is the MOLD? - CONTENTS: How to Estimate the Age of Mold Contamination in buildings. A mycologist's view on setting an age on mold in buildings. A building scientist's view on setting an age on mold in buildings.
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How old is the mold growth:
This building mold contamination assessment article discusses how we can estimate the age and history of mold contamination in a building and
how we can find evidence suggesting that a given mold contamination case is new, old, or includes both
old and new fungal growth.
The appearance of mold genera/species varies widely as a function of the growth substrate (paper, wood, cloth) and moisture conditions.
How Old is This Mold? Is it Possible to Determine the Age of Mold in buildings?
For insurance adjusters, building investigators, and building owners, a common question that arises when reviewing building mold contamination is "when did this happen" or "did the recent building leak or problem cause all this mold?".
Here we explain how an experienced forensic investigator can find visual evidence that a mold problem in a building is of recent origin or if on the other hand the mold contamination in an area has been most likely present for a much longer time.
We will discuss: building conditions affecting the genera, species, and rate of fungal growth in buildings. Conditions permitting an assessment of probable age of mold growth in buildings. How to evaluate mold samples for indications of active mold growth. Evidence of Mold History in buildings, Evidence of Mold Age in Laboratory Samples. Insurance claims & water entry history & mold damage causation analysis.
A Single-leak event mold example
The mold photos above show the extent of fungal growth in a home which had no previous mold nor leak history but
which experienced a burst-pipe flood followed by six months of inattention before an insurance claim was filed.
Thick fungal growth was present on
some surfaces, and some fungal growth was present on most materials and surfaces with genera/species varying considerably
depending on just what surface we examined.
For example, the edge of a door hosted a different genera/species than
the face of the same door (different woods). (We conducted a survey to study just what fungal genera/species
preferred just which building materials in this home.)
Was this mold due only to the burst pipe?
The absence of other indications of recurrent water entry or rot
supported the view that although the fungal growth was extensive, it was in response to a single event.
A multi-event long-standing leak condition mold example
The mold photos above show thick dense fungal growth on rotted wood in a second building.
At the top of this page, a photo of similar-looking fungal growth as that shown in the "single-leak" case cited just above
(by size, thickness, and extent below a wood subfloor) was
was taken in a second building which had suffered decades of water entry.
It was much less likely that the mold growth we saw in the
second building was due only to a single event flood.
Data like this can assist building owners and insurance claims adjusters in forming a reasonable opinion about the cause and age
of mold contamination in a building.
In turn, that opinion can assist in setting priorities for building repair since if we
do not correct the underlying causes for mold contamination in a building, mold growth is likely to recur and the investment
in a given mold remediation project may be wasted.
A mycologist's view on setting an age on mold in buildings
Mycologists indicate and field experience by property inspectors confirms that fungal growth can occur in a building over a
broad surface and quite rapidly, in as short a time as 2-3 days in some conditions
and they add that it is not very reliable to guess at the "age" of a given mold colony.
Of course there are exceptions: some fungal growth such as "tree ears" and hard fungi produce slow-growing and durable structures over many years - the larger their size the older they are. But in general, mycologists are precisely correct: looking at a sample mold itself does not easily permit us to guess how long mold has been present on that surface.
A building scientist's view on setting an age on mold in buildings
But the good news for building forensic analysis is that other accompanying observations in a mold-contaminated building can provide compelling evidence regarding the age of mold infection there.
A building scientist, particularly if s/he has also some training in mycology, can in some cases sort out the probable
history of mold contamination in a building by using evidence from a variety of supporting sources.
Most buildings more than just a few years old are likely to have experienced an occasional spill, leak, or
other source of water entry which could, in turn, have been a gating factor in developing problematic mold
growth in the structure.
Buildings more than 20 years old, particularly wood-frame structures and structures which
use interior materials which are "mold friendly" such as drywall, fiberglass insulation, and carpeting, often have had
more than one leak, wetting or flooding event and may have more than one location and source of mold growth.
fact a careful inspection of most homes, even ones which have never reported a flood or mold problem, can quite often, perhaps
usually, find some spot of fungal growth in the structure. (That does not necessarily mean that the building has a "mold problem".
In all but the most egregious and uncommon cases such as brand new construction which has been flooded,
a hasty, superficial scan of a building or of visible mold in it should not alone be a basis for deciding whether or not
a mold problem has been long-standing or has occurred only as the result of a single most-recent building leak or flood.
However, thoughtful observation and recording of certain building conditions along with careful,
thorough site and laboratory work can provide insight into the probability that mold found indoors
at a particular building and at a particular time is probably due to a specific building wetting event or, on the contrary,
that mold in a building, or at least some of it, probably pre-dates the specific wetting or flooding event.
Conditions affecting the genera, species, and rate of fungal growth in buildings
The appearance of mold genera/species varies widely as a function of the growth substrate (paper, wood, cloth) and moisture conditions.
Different species prefer different moisture levels and thus may appear on the same material such as drywall but at different
heights from the floor if that section of drywall was wet from the floor level. (Stachybotrys chartarum prefers very wet conditions and
appears low on the wall.
In the extremely mold-contaminated building shown at left, the author tested every surface of every different type of building material found inside the structure.
The results were interesting: different mold genera/species had strong preferences for different materials (no surprise).
Cladosporium and Ulocladium are often found somewhat higher on the same wall. Aspergillus sp. or Penicillium sp. often prefer still less wet conditions and may be found higher still or more uniformly spread
over a drywall surface as they may grow more readily in conditions of high humidity even if the drywall was not actually wet to the touch.
What produces mold growth on a building surface is the combination of this presence of omnipresent
fungal spores available in the general environment, the presence of a building material that a particular fungus will
grow on (its food), and the presence of appropriate conditions of moisture and, to a lesser degree, temperature and
perhaps light or darkness.
If these mold-conducive conditions have been present in a building for months or years,
the probability that a fungal growth has appeared suddenly and as a sudden and brand-new mold colony is rather low.
Conditions permitting an assessment of probable age of mold growth in buildings
All of these mold-producing conditions are likely to pertain and should always
considered in both field and laboratory examinations of moldy conditions in any building where mold contamination is present.
Of course for any specific case of mold contamination in a building, only some of these conditions will actually
be present and determinant of mold growth in a particular building and case.
Water leak history sets a probable age of mold
Evidence of a history of recurrent water entry in a building will establish that mold-producing conditions have been present since the beginning of those water or wet conditions in and at the property. These include both:
Evidence of water-entry producing conditions (missing gutters, in-slope grade, improper ventilation, history of plumbing leaks, multiple flood lines in a building) and
Evidence of the effects of water entry (water stains, damage from rot or insects, visible mold). Mold spores are available in the environment nearly all of the time under all conditions.
Evidence of rot sets a probable age of mold
Evidence of rotted wood components such as flooring, framing, floor joists, sill plates, or posts.
While water entry can occur suddenly and can be extreme (flooding, burst piping, sudden severe roof leaks), the conditions produced by a first-time and one-time event, if inspected days, weeks, or even several months after the event, will not include rotted components.
The floor trim in the photo above is not only moldy, a closer examination shows that it has rotted.
The rotted condition of the trim indicates long-term exposure to water and makes it less likely that the mold on the trim is
due only to a single recent leak event.
The photo above examines the wall cavity behind this rotted floor trim, showing
additional wood debris and mold growth on the cavity side of drywall in this building.
Evidence of exfoliating rust sets a probable age of mold
Evidence of exfoliating rust on steel components such as steel Lally columns, teleposts, or steel heating furnaces or boilers, is evidence of recurrent or protracted wet conditions which are also mold-conducive.
"Exfoliating" or thick flaking rust, or even rust penetration of components, is to be distinguished from light, superficial rust that appears readily on unprotected metal surfaces after a single wet event.
The photo at above left shows no building-related rust on a steel lally column in a dry crawl space. This area has not
been subject to severe recurrent water entry. The second photo at above right shows exfoliating rust on a steel lally column, clear
evidence that this space has been subject to recurrent and/or prolonged (many months) water entry.
Indirect evidence of moist conditions can suggest probable age of mold
The photo showing me pulling away perfectly-nice looking wall paneling to disclose a decades-old mold contamination issue from a single-event basement flood makes the point that that a single event that soaks a building can produce a large mold reservoir that might be left un-attended for a long time.
Evidence of wood destroying insect activity is suggestive of moist or wet conditions as those invite insects into a building; other conditions such as wood-soil contact are also factors in the development of insect damage.
Evidence of age of mold in the forensic microscopy laboratory
Condition of the mold or fungal colony itself, examined microscopically, may be suggestive of the length of time a mold infection has been present on a surface.
Dry desiccated fungal material is consistent with prior, currently inactive fungal growth on the surface which was sampled.
Fresh, hydrated fungal hyphae or fungal fruiting bodies (conidiophores or other sporulating bodies) are consistent with ongoing, current fungal growth. Some fungal bodies such as thick woody structures grow much more slowly and if present, almost certainly have been developing over a long time.
Of course, both types of fungal presence may be found on a surface, thus indicating that there is both a pre-existing moldy condition and current or renewed fungal growth.
Notes about these clues to the age of mold or mushrooms found in, on or around buildings (Identification of True Morel mushrooms)
[Click to enlarge any image]
In nature fungal growth can appear outdoors even more rapidly: some species of mushrooms may appear after a rainy night. The true morel mushroom shown in our photo (edible if properly identified) appeared just about overnight, sprouting up in a brick entry walkway
Rotted components from a single event leak may be present if the building has remained wet for more than a month or two, but that case can still be visually distinguished from prolonged water exposure, recurrent water exposure, multiple flooding events, and extensive deep rot in wood members by visual observation and experience.
Watch out: people have been seriously poisoned, even died, from eating improperly-identified or improperly-selected mushrooms. When in doubt, throw it out, don't eat it.
Watch out also: even edible mushrooms may vary widely in taste and appeal, not just by genera/species but by the mushroom's growing conditions and the make-up of its soil. I would not eat a mushroom that has been found on chemically-treated ground (which includes soil under some apple trees) or close to a public roadway where salt or other treatments have entered the soil.
Research on Edible True Morel Mushrooms & Poisonous False Morel Mushrooms
Braun, R., U. Greeff, and K. J. Netter. "Liver injury by the morel poison gyromitrin." Toxicology 12, no. 2 (1979): 155-163.
Hendricks, H. V. "Poisoning By False Morel (Gyromitra Esculenta): Report Of A Fatal Case" Journal of the American Medical Association 114, no. 17 (1940): 1625-1625.
Litchfield, J. H. "Morel mushroom mycelium as a food‐flavoring material." Biotechnology and Bioengineering 9, no. 3 (1967): 289-304.
McKnight, Kent H., Roger Tory Peterson, and Vera B. McKnight. A field guide to mushrooms: North America. Vol. 34. Houghton Mifflin Harcourt, 1998.
Michelot, Didier, and Bela Toth. "Poisoning by Gyromitra esculenta–a review." Journal of applied toxicology 11, no. 4 (1991): 235-243.
Molina, Randy, Thomas O'Dell, Daniel Luoma, Michael Amaranthus, Michael Castellano, and Kenelm Russell. "Biology, ecology, and social aspects of wild edible mushrooms in the forests of the Pacific Northwest: a preface to managing commercial harvest." (1993).
Nitha, B., C. R. Meera, and K. K. Janardhanan. "Anti-inflammatory and antitumour activities of cultured mycelium of morel mushroom, Morchella esculenta." Current Science (00113891) 92, no. 2 (2007).
Smith, Alexander Hanchett, and Nancy S. Weber. The mushroom hunter's field guide. University of Michigan Press, 1980.
Unambiguous, Ambiguous and Overlapping Mold Colonies in buildings
Especially in older buildings where there has been a recent sudden leak event associated with mold growth, it is often
possible to identify pre-existing mold as well as mold-producing conditions.
In unambiguous cases, the "new" mold associated
with the building leak event may, by luck, appear in a limited area of the building which maps the area wet by the recent leak,
and separated by distance or building area from other moldy areas which in turn are associated with other building leaks or conditions.
The physical separation of wet areas and wet conditions may be sufficient to make a clear assignment of mold causation in such cases.
In ambiguous cases, there is fresh, active fungal growth, probably associated with a recent leak or flooding event in the building, which
has grown entirely or partly overlapping pre-existing mold growth.
In this case the assignment of cause and age of mold in the building can
be ambiguous. If an insurance claim is involved, insurance company policy details and internal claims adjustment guidelines will determine the
extent to which insurance coverage will address building remediation and repair for these overlapped-occurrence mold conditions.
Determining Whether or Not a Mold Test Sample Shows Active Mold Growth
Question: how do we determine whether or not mold in a building is active vs. inactive?
Would you please let me know how an individual (or lab) would test for whether a mold found on attic sheathing is active vs. inactive?
Research on-line has told me the test for active vs inactive is whether it smears when you rub it. Is there a more technical test that can be done? Should a lab be able to tell me this when I supply a sample? - M.O.
The question of how we determine whether or not mold in a test sample is "active" is a bit misleading, although some surface test samples of mold do indeed give compelling evidence of recent active fungal growth.
Our site photograph of moldy roof sheathing (above) is an example. Is this mold growth "active" or "inactive", and does activity make much difference in risk to building occupants?
Here discuss visual clues that help determine the age of mold contamination in buildings or on building surfaces. There we explain what dried, desiccated, "old" mold growth may look like on a surface, in a test sample, and under the microscope. Among other factors, we distinguish between
Dry desiccated fungal material is consistent with prior, currently inactive fungal growth on the surface which was sampled. Very desiccated sample materials are almost certainly not indicators of active current fungal growth.
Fresh, hydrated fungal hyphae or fungal fruiting bodies (conidiophores or other sporulating bodies) are consistent with ongoing, current fungal growth. Some fungal bodies such as thick woody structures grow much more slowly and if present, almost certainly have been developing over a long time.
Often we can confirm recent fungal growth in a tape sample by the presence of certain growth structures, hyphal buds, or even the state of a conidiophore.
Our photo of Epicoccum sp. fungal spores and hyphae (above left) collected from a building surface shows intact, fragile hydrated complete spores still connected to hyphae - this mold growth is recent and might indeed be considered "active mold growth" as would the intact, hydrated, and budding Aureobasidium pullulans spores shown in our second lab photo (above right).
This burst of Pleospora spores is clearly active. Similarly, for certain species that produce long fragile spore chains, the presence of long mold spore chains is certainly indicative of nearby active fungal growth, as these chains break up rapidly into individual spores when airborne.
Conversely, highly desiccated, fractured, or damaged fungal material that lacks budding hyphae or sporulating intact conidiophores are almost certainly "inactive" mold growth in the spot where sampled.
Sources of Mistaken Conclusions about Mold Risk in Buildings
Watch out: "mold activity" or "mold inactivity" can be misleading conclusions about the risks associated with mold growth in buildings.
The moldy books in a college library (photo at left) were in the opinion of some people "an old inactive mold problem" but when workers began dehumidifying the area in preparation for a mold cleanup, visible clouds of Aspergillus sp. spores were released into the air by small air currents caused by simply walking down the aisle between stacks of books.
Mold test sample size: Because a sample represents a small area of a building and of time, and because other materials may be present that the sampler did not see, detect, or test, a single sample is an indicator, not a conclusion about a building's condition.
Multiple mold genera/species: Next, the conditions that produced fungal growth that was seen and tested mean that building conditions were ripe for mold growth, perhaps on other surfaces or in cavities or in less visible locations.
For example we may see one species of mold on an attic roof underside, say Cladosporium cladosporioides, perhaps even desiccated by the heat of sun beating on the roof, while the conditions that produced that growth also produced a non-visible but more troubling Aspergillus sp. contaminating growth in building insulation in the attic floor.
So at a given time, some mold on building surfaces may be "inactive" while nearby another genera/species may be growing like mad, or releasing spores like mad, i.e. "active".
Dead toxic mold: Next, we suspect an underlying faulty premise that the salient question is whether or not a fungal growth is active or not in a building. In fact even currently inactive (no apparent recent fungal propagation) fungal presence on a surface can be a hazard since spores and fungal hyphal fragments may be toxic, pathogenic, or allergenic even in that state.
That point remains true even if some misinformed "mold remediator" tries to "kill" the fungus with a fungicide or bleach.
Smearing mold?: Further, he claim that smearing mold with a finger determines whether or not it is active or not is nonsense.
A mold growth on a surface could be very desiccated and may not have actively propagated for a long time but still can be "smeared" with a finger wipe.
But we agree that if you cannot smear suspected-mold or better, if you cannot obtain particles on an adhesive tape sample, then the surface may have been previously cleaned, and what remains may be no more than a cosmetic stain.
Inoculation of mold: Finally, even if mold is "not actively growing" at the time that a sample is obtained from a surface (or in dust or air), the presence of a large amount of fungal material in a building can lead to rapid mold re growth and propagation when building conditions change to those more conducive to growth of the fungi already present.
All mold is everywhere all the time in the form of spores ready to inoculate a material or surface. So when building conditions are ripe for mold growth, it is likely to occur.
Predominantly, it is the building conditions that determine whether or not we will have a building mold problem, not the presence or absence of mold in general. But the presence of a large reservoir of pre-existing (inactive) mold can speed both the recurrence and the extent of a future mold contamination. "Inactive" does not mean "non-viable".
Watch out however: using a swab or culture test for "viable mold" in buildings can give very misleading results since what grows in the culture is what likes the culture, not necessarily what is present or dominant in the building.
These reasons explain why in addition to testing to confirm the presence of mold growth, and to confirm that it is not simply cosmetic, in cases of possibly costly mold cleanup or diagnosing a possible building contribution to indoor air quality complaints, is important to have an expert perform a competent inspection of the building.
Also see MOLD GROWTH on SURFACES for an index of what mold genera/species are frequently found on various building surfaces and materials.
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Question: rental unit is coverd in mold, how can I determine how long it's been there?
(June 9, 2016) Yvonne said:
I have a unit that was inspected 2 weeks ago and is now covered in mold. How can I find out how long it's been there?
My best suggestions are in the article above. If you see something in that article that raises a specific question just ask. I'm not sure what "inspected" meant 2 weeks ago; but a leak that wets building materials such as drywall can result in a serious mold contamination problem in 24-48 hours.
Question: scientific research about effects of bringing moldy stuff into a new home?
(Aug 31, 2016) Bazia said:
What if any science exists about inoculating the house we just bought by bringing items from the moldy house we are moving from. Lots of suggestions online of leaving everything behind to keep the next home healthy and uncontaminated.
There is certainly a possible problem with bringing in mold-contaminated materials into a new clean home as they may prove irritating or even a health hazard to occupants, depending on how sensitive the occupants are to the molds on the items imported and the amount of contamination. A client whose home I had investigated was in hospital after becoming seriously ill with mold-related respiratory illness. She was nearly recovered and was ready to return home. Her husband brought her a change of clothing that had been stored in a closet in the home. Exposure to the clothes was enough to send the client into severe respiratory distress.
But you do NOT need to abandon everything from a moldy home. That nonsense comes from people spending YOUR money to reduce THEIR RISK. I gripe about this problem in depth at inspectapedia.com/home_inspection/Other_Peoples_Money.php
Items of soft goods (clothes, bedding, towels) that can be laundered or dry cleaned should be fine.
items that are hard-surfaced can be washed - dishes, wooden furniture, metal objects.
Electronics like a stereo can be just surface-wiped or if very dusty HEPA vacuumed.
A mattress that was covered with bedding but that never was itself wet, covered with mold growth, nor smelly, can be HEPA vacuumed and salvaged.
Heavy upholstered furniture (couches for example) that was wet or moldy is not economical to clean, cannot be effectively cleaned, and would normally be abandoned. The cost to strip, clean the frame, and re-upholster it will usually exceed replacement cost.
I am less worried about inoculating the house itself. As my teacher, friend, mentor and NY State Mycologist John Haines used to exclaim, "all mold is everywhere, all the time" - that is, airborne spores are naturally-occurring in outdoor air and in building air. It is building conditions - dampness, wetness, leaks - that invite problem mold growth. Keep your new house dry and clean.
Longer term monitoring of previously flooded, mold contaminated homes does find indoor mold problems in many homes but in my experience it is almost always going to be due to incomplete demolition and cleaning.
Pearce, McGregor, Patrick H. Huelman, Kevin A. Janni, and Wanda Olsen. "Long-term monitoring of mold contamination in flooded homes." Journal of Environmental Health 58, no. 3 (1995): 6.
Chew, Ginger L., Jonathan Wilson, Felicia A. Rabito, Faye Grimsley, Shahed Iqbal, Tiina Reponen, Michael L. Muilenberg, Peter S. Thorne, Dorr G. Dearborn, and Rebecca L. Morley. "Mold and endotoxin levels in the aftermath of Hurricane Katrina: a pilot project of homes in New Orleans undergoing renovation." Environmental Health Perspectives (2006): 1883-1889.
Macher, Janet M., Fan-Yen Huang, and Martha Flores. "A two-year study of microbiological indoor air quality in a new apartment." Archives of Environmental Health: An International Journal 46, no. 1 (1991): 25-29.
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Questions & answers or comments about how to determine how old mold growth is in buildings
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Viitanen, Hannu, Juha Vinha, Kati Salminen, Tuomo Ojanen, Ruut Peuhkuri, Leena Paajanen, and Kimmo Lähdesmäki. "Moisture and bio-deterioration risk of building materials and structures." Journal of Building Physics 33, no. 3 (2010): 201-224.
There are several biological processes causing aging and damage to buildings. This is partly due to natural aging of materials and excessive moisture. The demands on durability, energy balance, and health of houses are continually rising. For mold development, the minimum (critical) ambient humidity requirement is shown to be between RH 80% and 95% depending on other factors like ambient temperature, exposure time, and the type and surface conditions of building materials.
For decay development, the critical humidity is above RH 95%. Mold typically affects the quality of the adjacent air space with volatile compounds and spores. The next stage of moisture-induced damage, the decay development, forms a serious risk for structural strength depending on moisture content, materials, temperature, and time.
The worst decay damage cases in North Europe are found in the floors and lower parts of walls, where water accumulates due to different reasons. Modeling of mold growth and decay development based on humidity, temperature, exposure time, and material will give new tools for the evaluation of durability of different building materials and structures.
The models make it possible to evaluate the risk and development of mold growth and to analyze the critical conditions needed for the start of biological growth. The model is also a tool to simulate the progress of mold and decay development under different conditions on the structure surfaces.
This requires that the moisture capacity and moisture transport properties in the material and at the surface layer be taken into account in the simulations. In practice there are even more parameters affecting mold growth, e.g., thickness of the material layers combined with the local surface heat and mass transfer coefficients.
Therefore, the outcome of the simulations and in situ observations of biological deterioration may not agree. In the present article, results on mold growth in different materials and wall assemblies will be shown and existing models on the risk of mold growth development will be evaluated.
One of the results of a newly finished large Finnish research project ‘modeling of mold growth’ is an improved and extended mathematical model for mold growth. This model and more detailed research results will be published in other papers.
Many of the following citations were suggested by the authors above - Ed.
Adan, O.C.G. ( 1994). On the Fungal Defacement of Interior Finishes, Thesis , Eindhoven University of Technology, Eindhoven, pp. 83-185.
Airaksinen, M., Järnström, H., Kovanen, K., Viitanen, H. and Saarela, K. ( 2007). Ventilation and Building Related Symptoms, In: WellBeing Indoors - CLIMA 2007, 10-14 June, Helsinki.
Ayerst, G. ( 1969). The Effects of Moisture and Temperature on Growth and Spore Germination in some Fungi, J. Stored Prod. Res., 5: 127-141.
Clarke, J.A., Johnstone, C.M., Kelly, N.J., Mclean, R.C., Anderson, J.A., Rowan N.J. et al. (1998). A Technique for Prediction of the Conditions Leading to Mould Growth in Buildings, Build. Environ., 34: 515-521.
Grant, C., Hunter, C.A., Flannigan, B. and Bravery, A.F. ( 1989). The Moisture Requirements of Moulds Isolated from Domestic Dwellings, Internat. Biodet., 25: 259-284.
Gravesen, Suzanne, Peter A. Nielsen, Randi Iversen, and Kristian Fog Nielsen. "Microfungal contamination of damp buildings--examples of risk constructions and risk materials." Environmental Health Perspectives 107, no. Suppl 3 (1999): 505. Abstract:
To elucidate problems with microfungal infestation in indoor environments, a multidisciplinary collaborative pilot study, supported by a grant from the Danish Ministry of Housing and Urban Affairs, was performed on 72 mold-infected building materials from 23 buildings. Water leakage through roofs, rising damp, and defective plumbing installations were the main reasons for water damage with subsequent infestation of molds.
From a score system assessing the bioavailability of the building materials, products most vulnerable to mold attacks were water damaged, aged organic materials containing cellulose, such as wooden materials, jute, wallpaper, and cardboard.
The microfungal genera most frequently encountered were Penicillium (68%), Aspergillus (56%), Chaetomium (22%), Ulocladium, (21%), Stachybotrys (19%) and Cladosporium (15%). Penicillium chrysogenum, Aspergillus versicolor, and Stachybotrys chartarum were the most frequently occurring species. Under field conditions, several trichothecenes were detected in each of three commonly used building materials, heavily contaminated with S. chartarum. Under experimental conditions, four out of five isolates of S. chartarum produced satratoxin H and G when growing on new and old, very humid gypsum boards. A. versicolor produced the carcinogenic mycotoxin sterigmatocystin and 5-methoxysterigmatocystin under the same conditions.
Hens, H.L.S.C. ( 1999). Fungal Defacement in Buildings: A Performance Related Approach. International Journal of Heating, International Journal of HVAC & R Research Ventilation, Air-Conditioning and Refrigerating Research, 5: 256-280.
Hope, Andrew P., and Ronald A. Simon. "Excess dampness and mold growth in homes: an evidence-based review of the aeroirritant effect and its potential causes." In Allergy and asthma proceedings, vol. 28, no. 3, pp. 262-270. OceanSide Publications, Inc, 2007. Abstract:
Exposure to fungi produces respiratory disease in humans through both allergic and nonallergic mechanisms. Occupants of homes with excess dampness and mold growth often present to allergists with complaints of aeroirritant symptoms. This review describes the major epidemiological and biological studies evaluating the association of indoor dampness and mold growth with upper respiratory tract symptoms.
The preponderance of epidemiological data supports a link between exposure to dampness and excess mold growth and the development of aeroirritant symptoms. In addition, biological and clinical studies evaluating potential causal substances for the aeroirritant effect, notably volatile organic compounds (VOCs), are examined in detail. These studies support the role of VOCs in contributing to the aeroirritant symptoms of occupants of damp and mold-contaminated homes.
Hukka, A. and Viitanen, H. ( 1999). A Mathematical Model of Mould Growth on Wooden Material, Wood Sci. Technol., 33: 475-485.
Hyvärinen, A., Meklin, T., Vepsäläinen, A. and Nevalainen, A. ( 2002). Fungi and Actinobacteria in Moisture-damaged Building Materials - Concentrations and Diversity, Int. Biodet. Biodegrad. , 49: 27-37.
Kalamees, T., Jokisalo, J., Kurnitski, J. and Vinha, J. ( 2007). Measurements and Simulations of Air Pressure in a Two-storey Detached House and in a Five-storey Apartment Building, In: IEA Annex 41 Working Meeting, 16-18 April, Florianopolis, Brazil, p. 8.
Kokko, E., Ojanen, T., Salonvaara, M., Hukka, A. and Viitanen, H. ( 1999). Moisture Physical Behaviour of Wooden Structures, VTT Tiedotteita 1991, p. 160 (in Finnish).
Kääriäinen, H., Rantamäki, J. and Tulla, K. ( 1998). Moisture Performance of Wooden Buildings, Feedback Knowledge of Actual Buildings, Technical Research Centre of Finland , Espoo, 85 pp. (VTT Research Notes 1923), 63 pp. + app. 14 pp. (in Finnish).
Land, C.J., Banhidi, Z.G. and Albertsson, A.-C. ( 1985). Surface Discolouring and Blue Staining by Cold-tolerant Filamentous Fungi on Outdoor Softwood in Sweden, Mat. Org. , 20: 133-156.
Leivo, V. and Rantala, J. ( 2006). Maanvastaisten rakenteiden mikrobiologinen toimivuus, Tutkimusraportti 139, Tampere, Tampereen teknillinen yliopisto, Rakennetekniikan laitos, 57 pp. + app. 55 pp. (in Finnish).
Leivo, V. and Rantala, J. ( 2008). Microbiological Aspects of Slab-on-ground Structures , In: Proceedings of the BEST 1 Conference, 12-13 June, USA: Minneapolis.
Lähdesmäki, K., Vinha, J., Viitanen, H., Salminen, K., Peuhkuri, R., Ojanen, T. et al. (2008). Development of an Improved Model for Mould Growth: Laboratory and Field Experiments, In: Proceedings of 8th Nordic Symposium on Building Physics, Copenhagen.
Ojanen, T. and Salonvaara, M. ( 2000). Numerical Simulation of Mould Growth in Timber Frame Walls, In: Seppänen, O. and Säteri, J. (ed.), Healthy Buildings , Vol. 1, 6-10 August, FiSIAQ , Espoo, FI.
Niemeier, R. Todd, Satheesh K. Sivasubramani, Tiina Reponen, and Sergey A. Grinshpun. "Assessment of fungal contamination in moldy homes: comparison of different methods." Journal of occupational and environmental hygiene 3, no. 5 (2006): 262-273. Abstract:
In an effort to better understand the relationship between different fungal sampling methods in the indoor environment, four methods were used to quantify mold contamination in 13 homes with visible mold. Swab, fungal spore source strength tester (FSSST), and air samples (total of 52 samples) were analyzed using both the microscopic (total spore count) and culture-based (CFU count) enumeration techniques. Settled dust samples were analyzed for culturable fungi only, as the microscopic enumeration was restricted by the masking effect.
The relationships between the data obtained with the different sampling methods were examined using correlation analysis. Significant relationships were observed between the data obtained from swab and FSSST samples both by the total counting (r = 0.822, p < 0.05) and by the CFU counting (r = 0.935, p < 0.01). No relationships were observed between air and FSSST samples or air and settled dust samples. Percentage culturability of spores for each sampling method was also calculated and found to vary greatly for all three methods (swab: 0.03% to 63%, FSSST: 0.1% to > 100%, air: 0.7% to 79%).
These findings confirm that reliance on one sampling or enumeration method for characterization of an indoor mold source might not provide an accurate estimate of fungal contamination of a microenvironment.
Furthermore, FSSST sampling appears to be an effective measurement of a mold source in the field, providing an upper bound estimate of potential mold spore release into the indoor air. Because of the small sample size of this study, however, further research is needed to better understand the observed relationships in this study. Keywords: air sampling, indoor fungi, settled dust
Ojanen, T., Kohonen, R. and Kumaran, M. ( 1994). Modeling Heat, Air and Moisture Transport Through Building Materials and Components, In: Trechsel, H.R. (ed.), Moisture Control in Buildings, pp. 18-34, ASTM American Society for Testing and Materials, Philadelphia .
Paajanen, L. and Viitanen, H. ( 1989). Decay Fungi in Finnish Houses on the Basis of Inspected Samples from 1978 to 1988, The International Research Group on Wood Preservation, IRG Doc. No: IRG/WP/1401, p. 4.
Ritschkoff A.-C., Viitanen, H. and Koskela, K. ( 2000). The Response of Building Materials to the Mould Exposure at Different Humidity and Temperature Conditions, In: Seppänen, O. and Säteri, J. (ed.), Healthy Buildings 2000, Vol. 1, 6-10 August, Finnish Society of Indoor Air Quality and Climate (FiSIAQ), Espoo, FI, pp. 317-322.
Sedlbauer, K. and Krus, M. ( 2003). A New Model for Mould Prediction and its Application in Practice, In: Carmeliet, J. et al. (ed.), Research in Building Physics, Proceedings of 2nd International Conference on Building Physics, Leuven .
Sedlbauer, K. ( 2001). Prediction of Mould Fungus Formation on the Surface of/and Inside Building Components, University of Stuttgart, Fraunhofer Institute for Building Physics, Doctoral Thesis, Stuttgart , Germany.
Seltzer, James M. "Biological contaminants." Journal of allergy and clinical immunology 94, no. 2 (1994): 318-326.
Abstract: The potential economic impact of indoor air pollution is quite high and is estimated in the tens of billions of dollars per year. Such impacts includes direct medical costs and lost earnings due to major illness as well as increased employee sick days and lost productivity.” The health consequences of biological contamination range from uncomfortable odors to end-stage lung disease to fatality. What factors predispose to biologic contamination? Which contaminants cause adverse health effects? What illnesses are associated with which contaminants, and how do these occur? This discussion will help answer these questions, leaving the discussion of environmental sampling, interpretation of sampling results, and remediation to other speakers who presented this information. A few interesting ideas for consideration regarding the implications of biological contamination will also be presented. (J ALLERGYCLINIMMUNOL1994;94:318-26.)
Smith, S.L. and Hill, S.T. ( 1982). Influence of Temperature and Water Activity on Germination and Growth of Aspergillus restrictus and Aspergillus versicolor, Trans. Brit. Mycol. Soc., 79: 558-560.
Suonketo, J., Pessi, A.-M., Pentti, M. and Raunio-Lehtimäki, A. ( 1999). Betonielementtijulkisivujen mikrobiologinen toimivuus, Julkaisu 101, Tampere, Tampereen teknillinen yliopisto, Talonrakennustekniikka , 88 pp. + app. 6 pp. (in Finnish).
Theander, O., Bjurman, J. and Boutelje, J. ( 1993). Increase in the Content of Low-molecular Carbohydrates at Lumber Surfaces During Drying and Correlation with Nitrogen Content, Yellowing and Mould Growth, Wood Sci. Technol., 27: 381-389.
Viitanen, H. ( 1996). Factors Affecting the Development of Mould and Brown Rot Decay in Wooden Material and Wooden Structures, Effect of Humidity, Temperature and Exposure Time, Doctoral Thesis, Uppsala, The Swedish University of Agricultural Sciences, Department of Forest Products.
Viitanen, H. ( 2001a). Biodegradation of Cultural Heritage, State of the Art, Finland, In: ARIADNE Workshop: ‘Biodegradation of Cultural Heritage.’ 10-15 December, Prague, Academy of Sciences of the Czech Republic, ITAM - ARCCHIP, p. 7.
Viitanen, H. ( 2001b). Factors Affecting Mould Growth on Kiln Dried Wood, In: 3rd Workshop on Softwood Drying to Specific End Uses, Cost Action E 15, Advances in the Drying of Wood (VTT, Otawood), Vol. 4, 11-13 June, Helsinki, pp. 1-8.
Viitanen, H. ( 2004). Betonin ja siihen liittyvien materiaalien homehtumisen kriittiset olosuhteet - betonin homeenesto [Critical Conditions for Mould Growth in Concrete and Other Materials], VTT Working Papers: 6 (in Finnish, English Abstract).
Viitanen, H. and Ahola, P. ( 1999). La formazione della muffa su pitture a basso VOC [Mould Growth on Low VOC Paints], Pitture e Vernici Europe - Coatings , 75: 33-42.
Viitanen, H. and Bjurman, J. ( 1995). Mould Growth on Wood Under Fluctuating Humidity Conditions, Mat. Org., 29: 27-46.
Viitanen, H., Hanhijärvi, A., Hukka, A. and Koskela, K. ( 2000). Modelling Mould Growth and Decay Damages, In: Healthy Buildings, 6-10 August, Vol. 3, FISIAQ, Espoo, pp. 341-346.
Viitanen, H. and Ojanen, T. ( 2007). Improved Model to Predict Mould Growth in Building Materials , In: Thermal Performance of the Exterior Envelopes of Whole Buildings X - Proceedings CD, 2-7 December, Clearwater Beach, USA, ASHRAE, DOE, ORNL.
Viitanen, H. and Ritschkoff, A. ( 1991). Mould Growth in Pine and Spruce Sapwood in Relation to Air Humidity and Temperature, Uppsala, The Swedish University of Agricultural Sciences, Department of Forest Products , Report No. 221, 40 pp. + app. 9 pp.
Viitanen, H., Ritschkoff, A.-C., Ojanen, T. and Salonvaara, M. ( 2003). Moisture Conditions and Biodeterioration Risk of Building Materials and Structure, In: Proceedings of the 2nd International Symposium ILCDES 2003, Integrated Lifetime Engineering of Buildings and Civil Infrastructures, Kuopio, 1-3 December, 2003 RIL, VTT, RILEM, IABSE, ECCE, ASCE, Espoo, pp. 151-156.
Viitanen, H. and Salonvaara, M. ( 2001). Failure Criteria, In: Trechsel, E. (ed.), Moisture Analysis and Condensation Control in Building Envelopes, pp. 66-80, American Society for Testing and Materials ASTM MNL40, Philadelphia.
Vinha, J. ( 2007). Hygrothermal Performance of Timber-framed External Walls in Finnish Climatic Conditions: A Method for Determining the Sufficient Water Vapour Resistance of the Interior Lining of a Wall Assembly, Doctoral Thesis, Tampere, Tampere University of Technology, Department of Civil Engineering, 338pp. + app. 10 pp. Google Scholar
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home",
U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
"Disease Prevention in Home Vegetable Gardens,"
Department of Plant Microbiology and Pathology,
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: email@example.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones