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Mold-Resistant Interior Panels

Mold. It’s an unsettling issue that confronts drywall contractors and distributors quite often these days.

Talk of mold seems to be everywhere. Articles about construction damage or contamination due to moisture intrusion and the resultant growth of mold are front-page stories in trade journals and mainstream newspapers. And the fact that mold growth is caused by a variety of factors
can certainly create confusion for contractors
and suppliers.

One way to prevent possible mold problems
in interior walls is to thoroughly
understand the issue and the potential
solutions currently available in the

Mold development can result from any
source of water from leaky pipes or air
conditioners to moisture that becomes
trapped in wall cavities because of non breathable
material on the walls. With
so many different scenarios as to why
mold can be found in interior walls, you
might think mold growth can flourish
virtually anywhere. However, that’s just
not true. In order for mold to grow, four
conditions must be present simultaneously:
sufficient moisture, the correct
temperature range, mold spores and an
available food source. Remove any one
of these four factors, and you remove the
potential for mold growth.

The preferred food sources for molds are
organic materials. Recognizing this,
manufacturers of gypsum board panels
have developed new drywall products
that reduce the amount of organics and
thus reduce the food source for molds.
Products that feature inorganic materials
not only help contractors address the
mold issue, they also reduce the time
and expense of replacing or repairing
alternative products if they become wet
and at risk of growing mold.

One new gypsum board product on the
market has a traditional paper face but
uses fiberglass mats on the back of the
board, the side exposed to the stud cavity.
The theory here is that it is what’s
behind the wall that you can’t see that
can become troublesome. By the time
you realize if you ever do that there
is an intrusive moisture problem behind
the walls, mold may have already gained
a foothold there.

Another new interior panel product
goes a step further by removing the
paper from both the front and back of
the board and reducing the organics in
the core of the board. Utilizing fiberglass
mat facings on both sides, the result is a
highly inorganic board that provides
superior protection from moisture
intrusion problems. With the highest
resistance to mold on the market, this
board is ideal for hospitals, laboratories,
schools, healthcare facilities and other
structures where the concern for exposure
to mold growth may be particularly

How do you know if your gypsum
board offers resistance to mold growth?
The American Society for Testing and
Materials is an independent agency that
establishes test protocols so manufacturers
can demonstrate that specific
products meet specific standards. The
test for mold growth, ASTM D3273, is
the standard test method used by most
companies in the building products

During this four-week test, a sample of
the subject material, such as a gypsum
board, is placed in a closed chamber
along with potting soil and mold cultures.
With a constant temperature of
about 90 degrees and relative humidity
of 95 to 98 percent, the environment is
ideal for mold growth. Each week, the
testing laboratory monitors the gypsum
board and measures the extent, if any, of
mold growth.

At the conclusion of the test, the product
is reviewed on a scale of one to 10,
one being a high degree of mold growth
and 10 being virtually free of visible
mold. The higher the ASTM D3273
rating achieved by a product such as a
gypsum board, the more resistant it is to
mold growth. The new two sided fiberglass
mat product described above scores
a 10, the highest rating.

While there is no single solution to resolving
potential mold growth problems in
construction, the industry is developing
a number of best practices. By taking
immediate corrective steps in the event of
a leak, properly venting appliances,
checking out condensation spots and
using products engineered to resist the
growth of mold, contractors and distributors
should be able to rest easy.

About the Author

Chris Beyer is national marketing man-ager
for Atlanta based G-P Gypsum

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