Take Mold Out, Keep It Out

Al Draper

September 1, 2005

For buildings prone to mold issues, due to its types of operations or extreme local climate, mold prevention should be considered in the initial planning stages of construction. Although there is no way to definitively build a structure that will always be mold-free, there are a number of ways to help prevent it from growing and reoccurring.

Mold’s Affect on a Building and Its Tenants

Mold is a living, breathing organism that can exist without any visible indication for years. And because mold is a common allergen, it can cause a variety of health issues. Mold is believed to have a dose-response relationship with people: the more exposure, the more likely there will be health effects. However, there are no exposure limits enforced or even widely accepted guidelines, and people’s symptoms and sensitivities can vary widely. Most at risk are people with compromised immune systems, such as the young, the elderly and those with allergies and asthma.

For a building, mold can create problems, such as compromising the structural integrity, affecting resale value, causing the cost of insurance to rise, as well as creating negative aesthetics. Because mold can become latent for long periods of time and then reactivate, building owners and contractors must be diligent to clean and remove it to ensure it doesn’t return.

Special care must especially be exercised during the re-fireproofing process, when excessive moisture is introduced into the air, creating significant concern for mold growth. Proper preparation and project controls need to be implemented, such as the use of desiccant air dehumidifiers, which help combat the humidity introduced during this process.

Four Levels of Remediation

There are four basic levels of mold remediation projects, which are based on the severity of the problem and the amount of work needed to correct it.

Type A: Inspection and non-invasive activities. This includes, but is not limited to:

  • The removal of ceiling tiles and other minimal destructive techniques for visual inspection;
  • Bulk, tape and/or surface sampling; and
  • The establishment of containment barriers.

Type B:
Small-scale, short-duration activities that create minimal dust. This includes:

  • Stains on non-porous surfaces that can be wiped clean;
  • A small spot of growth on ceiling tiles or pipe insulation; or
  • A small spill on the carpet.

Type C: Remediation work that generates a moderate to high level of dust or requires demolition or removal of any fixed building components. Examples include:

  • Minor sheetrock removal and/or wall covering;
  • Significant removal of ceiling tiles and insulation above tiles;
  • Minor duct cleaning and other work above the ceiling;
  • Removal of non-cleanable carpet; and/or
  • Any individual remediation activity that cannot be completed within a single work shift or weekend.

Type D: Major remediation projects. These typically include:

  • Activities that require consecutive work shifts, and the potential for unauthorized personnel exposure;
  • Significant heavy mold growth throughout a building;
  • Aggressive species of mold present; and/or
  • Major contamination of the ductwork and the air handling system.

The severity of the problem must be determined before it can be properly addressed. You may want to seek professional help for all types of corrective action, but particularly for type C and D projects.

Preventing Mold’s Return

Once mold has been identified and removed, there are a number of steps that can be taken to try to prevent its return. Some of these will need to be completed during the construction or rebuilding phase, while others are ongoing processes and checks that need to be made. Many experts recommend using closed-cell or non-cellulose insulation to avoid moisture problems in the future, particularly in areas where moisture is likely to be present, such as around chilled water lines.

Other recommendations include:

  • Use a waterproof membrane as a barrier under roofing materials.
  • Spray drywall and beams with a wood protectant, allowing the surfaces to dry between coats for maximum effect.
  • Add mold inhibitors to paint in areas where mold is more likely to recur.
  • Don’t carpet areas prone to water, such as bathrooms and basements.
  • Increase and improve ventilation in areas with slow air movement.
  • Maintain humidity of 40 to 60 percent.
  • Maintain the roof and downspout system.
  • Make sure water is directed away from the foundation through the installation of drain tiles or downgraded landscaping.
  • Do not use vinyl wall coverings, which tend to trap moisture within the wall system.

Beware of Unnecessary Investments

Mold has become a hot-button issue over the last decade or so. In fact, according to the Mortgage Bankers Association’s Commercial/Multifamily Mold Working Group, in 2001, at least 10,000 mold exposure cases were filed in the United States and Canada, with some of the most high-profile cases occurring in California and Texas. The average remediation cost was estimated at $200,000 for commercial cases. While awareness is good, hype and misinformation may lead to unnecessary fears, overanalyzing a problem, or overengineering a solution, in addition to exorbitant insurance claims. Also beware of the proliferation of so-called “experts.”

Once building repairs and cleanup are complete, be sure to schedule regular checks, especially in the problem areas, for new mold occurrences.