
Vol. 75, No. 3, March 
2002
Out of the Dark: The Emergence of Toxic Mold Litigation
Wisconsin law gives little direct guidance to plaintiffs and 
defendants on determining whether insurance policy exclusion clauses 
will operate to exclude toxic mold claims. With the rise in toxic mold 
litigation, perhaps one or more appellate decisions will assist lawyers 
in advising their clients on the probability of coverage.
 
by John Mitby & Kevin Trost
 Mold claims arising out of water damage to 
property have significantly increased in the last year. A spokesperson 
for Farmers Insurance has estimated that mold claims for the year 2001 
will be more than five times the number of claims for the year 2000 and 
total $85 million.1 Toxic mold has attracted 
the attention of the public and media as more individuals have started 
complaining that their illnesses and ailments can be traced to their 
exposure to certain molds in their homes or workplaces. With these 
individuals now seeking legal redress for property damage and for their 
ailments, some attorneys consider that the rapid proliferation of mold 
lawsuits will soon rival the recent lead paint or asbestos 
litigation.2
Mold claims arising out of water damage to 
property have significantly increased in the last year. A spokesperson 
for Farmers Insurance has estimated that mold claims for the year 2001 
will be more than five times the number of claims for the year 2000 and 
total $85 million.1 Toxic mold has attracted 
the attention of the public and media as more individuals have started 
complaining that their illnesses and ailments can be traced to their 
exposure to certain molds in their homes or workplaces. With these 
individuals now seeking legal redress for property damage and for their 
ailments, some attorneys consider that the rapid proliferation of mold 
lawsuits will soon rival the recent lead paint or asbestos 
litigation.2
Injured parties have sought recovery through first-party claims 
against their own property and homeowner insurers and have brought bad 
faith claims when their insurers have refused to properly address mold 
claims. There also have been an increasing number of third-party claims 
brought by injured parties and insurers in subrogation actions against 
those allegedly responsible for the development of the mold. Among those 
named in such complaints are contractors whose shoddy construction 
practices have allowed moisture to seep into building interiors, 
architects and engineers for substandard building designs, and even 
lumber companies and paint manufacturers for not providing products that 
resist mold. These defendants subsequently have sought coverage under 
their own policies.
Against this backdrop, attorneys for both plaintiffs and defendants 
are now confronting a variety of insurance policy exclusion clauses that 
were rarely interpreted with mold in mind. This article provides a brief 
overview of the toxic mold litigation creeping into the courts and 
highlights how Wisconsin courts have interpreted standard insurance 
clauses central to analyzing whether insurance coverage is present.
What is Toxic Mold
Mold is all around us - in the air, in the walls, below the flooring, 
and above the ceiling tiles. While many varieties of molds are harmless, 
a few varieties emit poisonous mycotoxins that can cause a range of 
health problems when a person is exposed to them in high concentrations. 
So far, the Centers for Disease Control has identified 25 "toxic molds" 
out of the 3,000 known molds.3 The most 
well-known of the toxic molds is stachybotrys chartarum, which 
is a black-colored mold that often is found inside walls. However, 
significant research remains to be performed on several molds to 
determine their toxicity. Experts now are evaluating the toxicity of 
other molds, including cladosporium, commonly found as a form 
of mildew on walls, and aspergillus, which can be found on 
wooden furniture.4
Toxic mold can become a health risk if it is allowed to grow and 
multiply inside an environment containing a source of moisture and food. 
The breakneck pace of construction throughout the 1990s allowed many 
homes and buildings to be constructed with defects that allow water and 
moisture to seep into the interior. Once the toxic mold has migrated 
inside otherwise tightly sealed homes and buildings, it encounters a 
perfect environment for growth because there are minimal 
water-evaporating drafts and abundant sources of food. Molds consume 
cellulose, which is present in such common building materials as wood, 
paper, ceiling tile, drywall, and cardboard.5
When toxic mold has grown and spread, it releases into the 
environment mycotoxins that can affect human health if present in 
sufficiently high concentrations. Published studies confirm that 
exposure to high concentrations of mycotoxins can produce respiratory 
ailments and irritations of the eyes, nose, and throat, and aggravate 
asthma.6 Recently, however, individuals also 
have alleged that in severe cases toxic mold has caused bleeding lungs, 
memory loss, and chronic fatigue syndrome. With few published studies 
analyzing the extent of toxic mold's health effects, causation of these 
more serious health effects is a hotly contested issue. As Jon Woods, an 
associate professor of microbiology at the U.W.-Madison, acknowledged, 
"A cause and effect link is difficult to establish ... I'm not saying 
it's not true. I'm just saying it hasn't been proven."7
Toxic mold also poses a danger to the property that it grows on and 
to property near an infestation. Porous items in the vicinity of the 
toxic mold often must be destroyed because they can harbor toxic mold 
spores. In extreme cases the toxic mold can become so pervasive 
throughout a house or building that remediation is impossible. In that 
situation, the house or building often is razed. In the state of Oregon, 
a couple whose home was infested with toxic mold allowed a local fire 
department to use their home for a test burn training exercise for 
firefighters.8
Rise in Mold Litigation
To date, the South has been most affected by mold litigation, because 
the humid and warm climate is more conducive to mold growth. Not 
coincidentally, courts in Southern states also have decided the most 
cases and entered the most jury verdicts for plaintiffs. In Florida, a 
jury awarded $11.5 million against a builder of a county courthouse 
where shoddy construction allowed the introduction of toxic mold that 
sickened county employees.9
A Texas case has attracted the most attention to toxic mold. In 
Ballard v. Fire Insurance Exchange,10 a couple and their 3-year-old son grew ill after 
their insurer mishandled a claim for fixing leaking plumbing. The couple 
had asked their insurer to replace a subfloor in their home after 
noticing that their floors had buckled from the plumbing leak. A 
contractor also recommended replacing the floor because of the danger of 
mold contamination. The insurer refused, and the family later grew 
terribly ill after mold spread from the subfloor throughout the house. 
Ultimately, the house had to be razed, because the mold had become so 
pervasive that remediation was infeasible. A Texas jury found that the 
insurer had acted fraudulently by not properly handling the leak and 
mold problems, and awarded the couple more than $32 million in 
compensatory and punitive damages. The insurer is appealing the 
verdict.
Wisconsin courts are beginning to confront a rising number of mold 
claims. A Waukesha County family recently alleged that toxic mold 
developed from leaky windows in their new home and was the source of 
their illnesses, including a serious attack on their son's immune 
system.11 The family had to move from the 
home and is bringing suit against the persons from whom they purchased 
the home.12 A Dane County family sued its 
insurance company after the insurer failed to reimburse the family for 
all the personal property it disposed of while remediating the family's 
mold-infested home.13 Potential claims also 
are in sight: A newly constructed Madison school had to be evacuated and 
students relocated to other schools for many weeks after mold was 
discovered in the building walls.14 See 
Mold in Wisconsin Schools.
In the wake of several large jury verdicts, insurers are reexamining 
how mold is treated under their policies. A number of insurers are 
attempting to more explicitly exclude mold damage from their homeowners' 
policies in the most heavily affected states. The remainder of this 
article examines the more common insurance clauses applicable to both 
first-party and third-party mold claims and how Wisconsin courts have 
interpreted them.
Mold Exclusion Clause
The Insurance Services Office (ISO) publishes model policies that 
form the backbone of the policies offered by individual insurance 
companies. The 1991 HO-3, the most common homeowners' policy, contains 
the standard policy language at the heart of most homeowners' policies. 
Coverage is extended for certain structures if there is "direct physical 
loss" to the covered property. While mold is capable of producing such a 
direct physical loss, an exclusion clause states: "We do not insure, 
however, for loss: ... 2. Caused by: ... (3) Smog, rust or other 
corrosion, mold, wet or dry rot." This exclusion clause is referred to 
as a "wear and tear" clause, meaning that damage appearing over time and 
not as a result of an identifiable covered event does not trigger 
coverage under a policy.
While no Wisconsin cases and few cases nationwide discuss this clause 
in detail, those jurisdictions that have analyzed it have acknowledged 
coverage for mold where the proximate cause for the mold was a covered 
peril under the policy.15 In other words, 
if a homeowner's mold damage results from a leaky hail-damaged roof that 
the insurer paid to replace because hail was a covered peril, the mold 
remediation generally is covered because the original source of the mold 
was a covered peril. However, when there is no identifiable source for 
the mold other than homeowner neglect or inadequate cleaning procedures, 
the mold source cannot be traced to a covered peril and coverage is 
routinely denied.16
The ISO revised HO-3 in 2000 to more specifically address mold 
damage, and this exclusion clause is likely to appear in newly issued 
policies. The 2000 HO-3 exclusion reads:
"2. We do not insure, however, for loss: ... (c) Caused by: ... (5) 
Mold, fungus or wet rot. However, we do insure for loss caused by mold, 
fungus or wet rot that is hidden within the walls or ceilings or beneath 
the floors or above the ceilings of a structure if such loss results 
from the accidental discharge or overflow of water or steam from within: 
(a) A plumbing, heating, air conditioning or automatic fire protective 
sprinkler system, or a household appliance, on the `residence premises;' 
or (b) A storm drain, or water, steam or sewer pipes, off the `residence 
premises.'"
This clause explicitly acknowledges coverage for mold damage arising 
out of certain named perils, such as plumbing leaks, but remains silent 
as to other traditionally covered perils such as hailstorms. It can be 
argued that by not mentioning coverage for other perils the policy 
intends to exclude coverage for mold arising out of those perils not 
named. However, it is not certain that this language is sufficiently 
clear to achieve that result. Because the clause does not address mold 
caused by other covered perils, it can be argued that the clause is 
ambiguous and, therefore, should be interpreted in favor of coverage. 
Given that published decisions already have interpreted the predecessor 
HO-3 clause to allow coverage as long as the mold was caused by a 
covered peril, courts could reasonably interpret the present clause in 
the same manner, since there is no explicit language that would 
interfere with that interpretation.
Pollution Exclusion Clause
An insurance policy that does not include a mold exclusion clause is 
likely to contain the more general pollution exclusion clause. Both 
standard homeowners' and commercial general liability policies exclude 
coverage for damage caused by pollution. The 1991 HO-3 contains the 
standard pollution exclusion language, denying coverage for losses:
"2. Caused by: ... (e) any of the following: ... (5) Discharge, 
dispersal, seepage, migration, release or escape of pollutants unless 
the discharge, dispersal, seepage, migration, release or escape is 
itself caused by a Peril Insured Against under Coverage C of this 
policy."
Determining if toxic mold falls under this exclusion requires an 
analysis of whether toxic mold is a "pollutant" and whether there has 
been any "discharge, dispersal, seepage, migration, release or escape." 
If both conditions are met, then there is coverage if a covered peril 
caused the discharge, dispersal, and so on.
The only Wisconsin case to directly address mold in the context of 
the pollution exclusion clause is one of very few cases nationwide to 
address the issue and stands in the way of enforcing the clause. In 
Leverence v. United States Fidelity & 
Guaranty,17 several owners of manufactured homes sued 
the manufacturer and its insurer alleging that the exterior walls in 
their homes retained excessive moisture. The moisture allowed the growth 
of mold that posed a risk to health and property value.18 The 
Wisconsin Court of Appeals focused on the discharge and dispersal 
language in the pollution exclusion, stating that the exclusion did not 
bar coverage because the growth of the mold was the result of water 
vapor trapped in the walls.19 Accordingly, 
the contaminants were not "released" according to the policy "but rather 
formed over time as a result of environmental conditions."20 Because the mold did not disperse, discharge, 
and so on, according to the terms of the exclusion, the exclusion did 
not apply, and the court of appeals did not consider whether mold was a 
pollutant.
With an additional decade of research and attention to the 
microbiological aspects of mold, one now could more persuasively argue 
that toxic mold "releases" or "disperses" into the environment, since it 
gives off mycotoxins that cause human illness. It is yet to be seen if 
the Wisconsin Supreme Court will adopt this interpretation over the 
Leverence interpretation of more than a decade ago. However, a 
decade of additional scientific knowledge provides a basis for 
rethinking how mold is considered to cause injury under the pollution 
exclusion clause.
If a court goes beyond the Leverence interpretation of the 
discharge/dispersal language of the pollution exclusion clause, the 
question remains whether mold, and toxic mold in particular, is a 
pollutant. Wisconsin law provides no direct guidance for whether any 
mold is a pollutant. However, there is the potential for a comparison to 
carbon dioxide or lead paint, which were subject to relatively recent 
scrutiny by the Wisconsin Supreme Court.
In Donaldson v. Urban Land Interests,21 there was a challenge to whether the 
accumulation of carbon dioxide in a particular room in a building 
constituted a pollutant for purposes of the pollution exclusion clause. 
The court held that the carbon dioxide did not constitute a pollutant, 
since it is ever present in the atmosphere and "the respiration process 
which produces exhaled carbon dioxide is a necessary and natural part of 
life."22 It consequently refused to 
consider "carbon dioxide as in the same class as smoke, vapor, soot, 
fumes, acids, alkalis, chemicals and waste."23
The Wisconsin Supreme Court distinguished this analysis when it found 
lead paint to be a pollutant in Peace v. Northwestern National 
Insurance Co.24 In this case, a tenant 
sought recovery from the landlord for injuries her son sustained from 
ingesting lead paint particles.25 In 
declaring lead paint to constitute a pollutant under the pollution 
exclusion clause, the court distinguished Donaldson by 
explaining that lead paint is not universally present like carbon 
dioxide and historically has been considered harmful.26 It also determined that the flaking, chipping, 
and deterioration of the lead paint was "discharge, dispersal, release 
or escape within the meaning of the terms in the policy."27 Accordingly, the pollution exclusion clause 
effectively barred insurance coverage for the claim.
Toxic mold could be likened to lead paint, since its mycotoxins are 
harmful to human health and toxic mold is not universally present as is 
carbon dioxide. However, the fact that even toxic mold generally is not 
harmful to humans except in high concentrations affords an argument to 
support opposing viewpoints that would liken toxic mold to carbon 
dioxide, a nonpollutant, which also is not dangerous in low 
concentrations.
Conclusion
Plaintiffs and defendants currently have little direct guidance under 
Wisconsin law for determining whether insurance policy exclusion clauses 
will operate to exclude toxic mold claims. Hopefully, the recent influx 
of mold litigation will yield one or more appellate decisions on the 
coverage issues to assist practitioners in advising their clients on the 
probability of there being coverage for damage from toxic mold. 
Endnotes
1 Charles S. 
LiMandri, Epidemic of Mold Litigation Plagues Insurance 
Industry, Ins. Litig. Rep., July 12, 2001, at 262.
2 Toxic Mold: 
A Growing Legal Issue, United Press Int'l, Oct. 6, 2000.
3 Thor Kamban 
Biberman, Dormitory at San Diego State Closed Over Toxic Mold, 
San Diego Daily Transcript, July 2, 2001, page 1B.
4 Melissa A. 
Hortman & Mark S. Mason, The Next Wave, For Def., August 
2001, at 51.
5 Jennifer L. 
Reichert, Homeowners, Insurers Spar Over Spores in Toxic-Mold 
Cases, Trial, Sept. 2001, at 14.
6 Wisconsin 
Realtors Association, What You Need to Know About Mold, Legal 
Update, no. 1.07 at 4; Federal-Provincial Working Group on Mycological 
Air Quality in Public Buildings, Fungal Contamination in Public 
Buildings: A Guide to Recognition and Management (Ottawa, Ontario, 
Canada: Federal-Provincial Committee on Environmental and Occupational 
Health, June 1995).
7 Paul Gores, 
Families Blame Mold for Making Them Sick, Milwaukee J.-Sent., 
July 8, 2001, at F1; see also U.S. Centers for Disease Control, 
Reports of Members of the CDC External Expert Panel on Acute 
Idiopathic Pulmonary Hemorrhage in Infants: A Synthesis 
(Washington, D.C.: CDC, Dec. 1999) (Centers for Disease Control could 
not scientifically confirm allegations that stachybotrys 
chartarum was the cause of the pulmonary hemorrhages and deaths of 
16 Cleveland, Ohio, infants).
8 O'Hara v. 
Lockram, No. 16-00-12848 (Ore. Cir. Ct. Lane County).
9 
Centex-Rooney Constr. Co. v. Martin County, 706 So. 2d 20 (Fla. 
App. 4 Dist. 1997).
10 Ballard 
v. Fire Ins. Exch., No. 99-05252 (Tex. Dist. Ct. Travis County June 
1, 2001).
11 Gores, 
supra note 7, at F1.
12 Droegkamp 
v. Langdon, No. 01-CV-2803 (Wis. Cir. Ct. Waukesha County Nov. 21, 
2001).
13 Bodway v. 
United Serv. Auto. Ass'n, No. 01-CV-1326 (Wis. Cir. Ct. Dane County 
May 17, 2001).
14 Lisa Schuetz, 
Parents Push for Answers about Closing of Chavez, Wis. State 
J., Dec. 19, 2001, at A1.
15 
Sunbreaker Condominium Ass'n v. Travelers, 79 Wash. App. 368, 901 
P.2d 1079 (1995) (mold damage covered if cause was wind-driven rain); 
Bowers v. Farmers Ins. Exch., 99 Wash. App. 41, 991 P.2d 734 
(2000) (mold damage covered when cause was tenant's vandalism); 
Merrimack Mut. Fire Ins. Co. v. McCaffree, 486 S.W.2d 616 (Tex. 
Ct. App. 1972) (mold damage not covered when water had leaked over many 
years from improperly constructed shower stall).
16 Wisconsin 
Realtors Association, supra note 6, at 8.
17 Leverance 
v. U.S. Fidelity & Guar., 158 Wis. 2d 64, 462 N.W.2d 218 (Ct. 
App. 1990).
18 Id. 
at 72.
19 Id. 
at 97.
20 
Id.
21 Donaldson 
v. Urban Land Interests, 211 Wis. 2d 224, 564 N.W.2d 728 
(1997).
22 Id. 
at 233-34.
23 
Id.
24 Peace v. 
Northwestern Nat'l Ins. Co., 228 Wis. 2d 106, 596 N.W.2d 429 
(1999).
25 Id. 
at 111.
26 Id. 
at 137.
27 Id. 
at 148
Wisconsin 
Lawyer