MOLD: An ounce of prevention really is worth a pound of cure
(First of a series)

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," Janesky said.

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."

Eliminating moisture

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 wall leaks.
  •  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 source."

Mold colonization

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 themselves."

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 voids."

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 concrete performance."

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 uptake models."

Keyser suggested thoughtful planning; a review of water entry prevention details and careful production consideration will do much to minimize exposure to mold litigations.

Christopher Brooks is a freelance writer based in Bucks County, Penn., writing about the home for consumer and trade magazines.

This article appears in the September 2003 issue of Concrete Homes.