MICROVENTED WALLCOVERING:
A PROACTIVE APPROACH TO DEAL WITH
MOLD and MILDEW
Mold and mildew are types of fungus which have been around since the beginning of time. Basically, molds are decomposers of dead organic
materials (biodegradables) such as wood, paper and plant matter. Although they can cause millions of dollars in damages; they nonetheless
play an essential role in maintaining our eco-system.
There are four conditions that must be present in order for mold spores to colonize and grow: namely, the presence of mold/mildew spores, a
food source, a moisture source and the proper room temperature (warmth). The elimination of any one of these four elements will curtail
mold/mildew growth. Since mold spores are everywhere and 90 percent are airborne, the likelihood of keeping any space mold free is near
impossible. Food is also readily available since mold/mildew spores can feed on any organic material. As for temperature, fungi thrive in the
same temperature range as people do (40-100°F) making extreme temperature an unsuitable solution. In order to resolve the conflict we
must turn to controlling moisture. “Without enough moisture, mold and mildew cannot absorb nutrients and grow, no matter how many spores
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are present”.
Under hot and humid conditions, warmer outside air is naturally drawn into the cooler side of an external wall through any tiny breach in the
building envelope when the building is air-conditioned. This can lead to condensation within the wall cavity, thus creating optimum conditions
for mold/mildew growth.
“Although wallcoverings are often cited in connection with mold and mildew growth, it must be understood that wallcoverings do not cause
mold and mildew. In virtually all cases, the mold and mildew growth is due to excessive moisture. In order to prevent or eliminate mold and
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mildew, one must identify and eliminate the source of the excessive moisture”. The existence of fungal growth will typically result in pink or
black stains appearing on and/or behind the wallcovering, which is likely the reason why some people mistakenly believe that wallcovering is
the cause rather than the symptom of the “real problem” lurking behind the wall surface.
Mold/mildew can grow in most every climate just as long as the four elements are present; therefore, a permeable interior finish is desirable in
such instances where the likelihood is greatest. To accomplish this, Len-Tex has recently added the capability to “microvent” their
wallcoverings. Rather than the typical solid film face, this process punches 150 nearly invisible penetrations per square inch into the face. In
doing so, the microvented wallcovering allows moisture to diffuse through the wall to the cooler side of the interior. The building HVAC system
then performs its dehumidification process, reducing the probability of the wall cavity reaching the dew point, hence preventing water
condensation within the wall.
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Published permeability requirements seek a rating of 5 perms or greater for interior walls . Len-Tex has had their “microvented”
wallcoverings tested by an independent lab for “Water Vapor Transmission of Materials” in accordance with ASTM E 96-00. The test results
conclude that “microvented” wallcoverings by Len-Tex exceeds a permeance rating of 15.0 perms.
All Len-Tex wallcoverings and the adhesives we recommend to install our products contain mildew inhibiting additives. You can and should
include references within your specification documents that all wallcoverings must have passed the Fungal Resistance Test in accordance
with ASTM G-21-96 and likewise request a copy of the test results.
Due to the multitude of wall system designs and climatic conditions, it is not possible for a wallcovering manufacturer to know whether
standard or microvented wallcovering is appropriate for a particular installation. Accordingly, the permeability data of microvented wallcovering
is provided only as information to the specifier to ensure that it is compatible with the intended wall system design. Please contact your local
Len-Tex sales representative for further help with specifying “microvented” wallcoverings.
Downs, Peter “Vinyl and Mildew” Pg. 53; Painting and Wallcovering Contractor, July 1995
Position stated for the WA and CFFA Trade Associations, “Mold Cause, Effect and Response” Pg. 3’ The published findings of this collaboration to study mold,
2003
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Morey, Ph.D., Phillip R., “Poor Building Design leads to Fungal Growth” Pg. 2;
http://aerias.org/c-news-article_168.htm
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Federal register, Wednesday, April 24, 2002, Part IV, Housing and Urban Development Department, 24 CFR 3280, “Condensation Control for Exterior Walls of
Manufacturing Homes Sited in Humid and Fringe Climates; Waiver; Final Rule.
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