There is a general misconception about mold and water. Moisture by
itself does not cause mold. It needs specific elements working
together to grow. In concrete homes, structural damage cannot be
caused by mold. However, organic materials in the home such as wood,
drywall, etc. are subject to mold attack.
"The thing to do is prevent moisture from entering the home in
every way possible. In a new concrete home, this begins with proper
mold prevention. This means waterproofing," says Larry Janesky,
president of Basement Systems, an international network of basement
waterproofing and crawl space repair companies with headquarters in
Seymour, Conn. and holders of 16 patents for innovations in the
waterproofing industry. "There are different kinds - and colors -
of mold. Some may be harmless, but some mold spores are toxic and
cause various health problems. Mold can grow in a variety of
environments and on many organic surfaces."
Mold - always present
Mold is a necessary process of nature. "When it dies, a plant,
tree or animal decomposes. Mold feeds on this organic matter, which is
nature's way of recycling nutrients back into the soil. Spores - the
seeds of mold - are present everywhere and all of the time,"
Any air current will carry spores. These can remain dormant for
many years and suddenly become active under the right conditions.
"Mold needs four things to grow," Dan Fitzgerald, vice
president of marketing at Basement Systems, said. "First, let's
consider what happens inside the home. Mold needs a surface that is
made of organic material. Wood, plywood sub-flooring, a floor joist;
even the paper facing on insulation and sheetrock are all organic
materials and are subject to mold attack. The other three 'players'
are the spores, moisture and the right range of temperatures. Mold
will thrive in a setting that is moist and humid."
Eliminating the possibility of mold in concrete homes is relatively
easy. "There is a single most important step we can take to
prevent mold from occurring in homes," he added. "The easy
answer is, simply put, to eliminate the possibility of moisture
entering the home. This is done at the time of construction. Without
moisture, mold will not grow."
When new homes have moisture problems, he notes these can usually
be handled in one of the following ways:
- Repair leaks, including roof leaks and basement floor or
- Fix plumbing leaks quickly. Remove the water. Dry it out
as soon as possible. Mold takes a couple days to become active.
Fans and dehumidifiers can be used to restore a dry setting.
- Crawl space needs attention. If the home has a dirt crawl space,
it needs to be encapsulated to isolate it from humid soil. Crawl
space vents can be sealed.
"Building homes with concrete helps a great deal, Fitzgerald
said. "However, we still use organic materials such as wood and
sheetrock. If these organic materials in homes get wet and remain damp
for more than a couple days, mold can begin to grow.
"It's vital to keep the interior of the home dry. This doesn't
mean to just keep them - the organic materials - from getting soaked.
It means any environment with humidity of more than 55 percent."
Today the subject of mold is an attorney's dream. Fitzgerald
concludes, "Ignore the mold issue and you do so at your own risk.
Presently there are about 10,000 open lawsuits stemming from claims
regarding mold problems. Insurance companies are writing mold
exclusions into their policies. The best way to deal with mold is to
effectively waterproof the home during its construction. In this day
and age, there is no reason why every new home doesn't come with a dry
basement wall and floor warranty."
Mold problem overstated?
Stephen Keyser, a 24-year veteran of waterproofing, roofing and
conservation issues and president of CRW Co. in Seattle, said that
it's true that there is a litigation onslaught of judgments being
levied against builders and designers.
"One can argue that the cause for 'mold' is overstated, that
there is little or no scientific data to support this litigation; but
the wrong place to argue the issue is in a civil court as a
defendant," said Keyser, whose company is the representative in
the Pacific Northwest for Xypex Chemical Corp., developer and
manufacturer of Xypex Crystalline Technology for waterproofing and
repairing concrete, based in Vancouver, British Columbia in Canada.
"We know that mold needs three essential things - a food
source, a water supply and a compatible temperature. Concrete does not
provide a food source. Cellulose is the big dinner bell. The
construction process itself may provide much of the needed food
Preventing the establishment of mold colonies is vital. "These
hardy organisms have been around for millions of years," Keyser
said. "It is the spores that are considered to be the most
threatening source of potential injury or harm. When the organism
experiences a diminishing of water or food sources, spores are
released to insure survival of a later generation. They can remain
viable for decades, waiting for the proper conditions to reestablish
Adverse temperatures are not considered to be a useful variable for
control. Watertight construction is essential. Interior and ceiling
finishes are all common sources of colonization.
Concrete is not waterproof by itself. "The water needed to
hydrate a concrete batch is really fairly minimal. It is the water
that imparts plasticity for movement and workability that is the
culprit. What is not consumed eventually leaves the concrete via bleed
or evaporation. What is left behind is a network of capillary tracts.
The higher the cement to water ratio, the more prolific the capillary
It has been his experience through the years that residential
constructions are the most prone to leaks through concrete at or below
the grade line.
"Many of the advances in minimizing concrete porosity,
plasticizing agents in particular, and waterproofing admixtures are
poorly communicated to the builder. The concrete finishers love
plasticity, the more plastic the concrete the easier it is to move and
work. Reaching for the water hose to increase mix plasticity is a
fairly common choice. Regrettably, some refuse to entertain the
proposal that a better concrete design is worth some additional cost.
The mold issue is rapidly changing the resistance to improving
Building out mold
Keyser emphasizes that the building envelope does not stop at the
grade line. "It continues down to the footings and under the
slab. The first step in 'building out' mold is to recognize the
importance of waterproofing below the grade line. It is not, in my
opinion, justifiable to substitute a damproofing system for
waterproofing below grade. Waterproofing mediums have been tested to
rigorous protocols. The key is pressurized testing, not absorption and
Keyser suggested thoughtful planning; a review of water entry
prevention details and careful production consideration will do much
to minimize exposure to mold litigations.