THE COHEN GROUP
  Environmental Health & Safety Consulting Services

The Cohen Group Newsletter - Volume 7  Issue 1, Article 1.  January, 2005

 With the rainy season now upon us, attention once again turns to the battle against water intrusion in the buildings we live and work in as they are periodically assaulted by heavy, wind-driven rains. Modern buildings are designed to keep moisture out, but moisture intrusion can occur through many types of penetrations in the building envelope (roof and exterior walls), because of deteriorated materials, failures in building systems, construction defects and even design flaws. Building systems deliver water to the locations where it is needed (e.g., fire sprinkler systems, bathrooms, kitchens and laundry areas), but moisture problems may arise from plumbing leaks and overflows, from incidental spills, or from other sources, such as high humidity and condensation, when interior areas are not properly ventilated.

When moisture accumulates on organic material (including organic debris and cellulose-based building materials) and conditions are favorable, mold growth may occur. And when mold growth is visible on surfaces or when mold-impacted materials are disturbed, mold particulate (spores, hyphae, fragments) and odors may be released. Consequently, indoor air quality may suffer if elevated levels are reached. Long-term moisture and mold accumulations can also result in deterioration of building materials.

Here are some simple steps to take to avoid such problems when encountering building materials that appear to be water damaged and may be contaminated with mold.

Control of Moisture and Mold

Mold is ubiquitous in the natural environment (outdoors) and grows on organic materials where environmental conditions (e.g., moisture, temperature, sunlight, etc.) are favorable. Since the outdoor air mixes with indoor air, some minor amounts of mold typically will be present in indoor environments as well. Mold can become a problem, however, when local environmental factors (moisture, temperature and presence of nutrients) favor significant mold growth and are allowed to persist.

The key to minimizing mold growth and its ensuing problems is the control of moisture. When building materials are kept dry, the mold spores that are "naturally" present on the surfaces of these materials will not reproduce and colonize the underlying materials (substrates).

General Prevention

A proactive approach to identifying and minimizing moisture intrusion is crucial. The following actions are recommended for any building owner:

Incident Response

When sudden water intrusion or a leak occurs, mold growth can generally be prevented through (1) immediate control of the water source, (2) prompt removal of accumulated water, and (3) removal and/or thorough drying of impacted materials, as long as such steps are taken within the first 24 to 48 hours of the onset of moisture accumulation. Visual and tactile evidence (dampness, staining, swelling, softening, warping, etc.) may be sufficient to identify the extent of impacted building materials, but other measures, such as testing with hand-held moisture meters may also be necessary.

Interior walls (drywall installed over metal or wood framing) around the building perimeter are most likely to suffer water intrusion and damage from exterior, weather-related events. Similarly, areas along the base of interior walls are susceptible to the impacts of floods, leaks, and spills, especially when the bottom edge of the drywall is at, or very close to, the floor surface, thus allowing water accumulations on the floor to contact and wick up into the gypsum board materials.

Immediate attention to and drying of building materials and furnishings (e.g., carpeting) is key to avoiding mold problems in these types of sudden event situations. When there is limited impact involving a small area, restoration may simply be a case of pulling up carpeting, using fans to help dry materials, and possibly removing a little drywall near the floor. Where the impacts are more severe and extensive, a professional restoration firm should be brought in to extract water from carpeting and deploy more sophisticated drying equipment.

In addition, the source of the released water must be identified and the category of water established to determine the appropriate response. Released or accumulated water is commonly categorized as follows:

Category 1 - Clean Water: Water that does not pose a substantial harm. Examples include water from broken supply lines, tub or sink overflows with no contaminants, broken toilet tanks with no additives, falling rainwater, and melting ice or snow. Note: Initially clean water may become contaminated upon contact with surfaces, soils, equipment, etc.

Category 2 - Gray Water: Water that contains a degree of chemical, biological and/or physical contamination and has the potential to cause discomfort or sickness if consumed. Examples include discharge from dishwashers or washing machines, overflows from toilet bowls with urine only, broken aquariums, punctured water beds, and seepage due to hydrostatic pressure.

Category 3 - Black Water: Water that is grossly unsanitary, containing pathogenic agents from sewage or other sources and likely to cause discomfort or sickness if consumed. Examples include overflows from toilet bowls containing feces, sewer backups (toilet backflows originated from beyond the toilet trap), seawater, ground surface water, and rising water from rivers and streams. Black water may also be contaminated with chemical agents.

Where gray or black water is known or suspected to be present, hazards from bacteria, viruses and other pathogens may exist and cleanup will require disinfection measures.

Longer Term Intrusion

Where wall areas are suspect or are likely to be disturbed, the following precautions should be taken:

1. Examine the wall surfaces for signs of water intrusion and deterioration, such as:
    - significant water staining,
    - bubbled/peeling paint that appears to be the result of moisture accumulation,
    - drywall that is soft to the touch (degraded) and/or appears to be significantly
      deteriorated,
   - wallpaper that has pulled away from the wall at the seams or corners and the wall
      surface visible behind the wallpaper appears to be deteriorated or
      possibly moldy, or
    - vinyl wall base ("cove") molding that has pulled away from the wall surface
      (and the wall surface visible behind the molding appears to be deteriorated
      or possibly moldy)

2. If any such signs are observed, stop work immediately. DO NOT disturb these materials.
    - DO NOT pull the base molding away from the wall to look for more damage
    - DO NOT cut or punch holes into the drywall to inspect for further evidence
      of mold

3. Inspect the area (a knowledgeable person) and determine if work can continue
    or if the work must be postponed until additional evaluations (e.g., by an outside
    specialist) are made.

The amount of fungal growth on interior surfaces to be cleaned, replaced or otherwise disturbed, as well as the likelihood of finding additional fungal growth determines the procedural requirements. It may be suitable to have facility personnel perform small-scale (i.e., low hazard) clean-up activities using minimal protective measures. However, when large-scale (high hazard) remediation is needed, specialty contractor personnel should conduct those operations and additional protective requirements will apply.

All interior remediation work should be performed in a manner that prevents emission of visible dust and fungi from disturbed surfaces into the living and work spaces. Plastic (polyethylene) sheeting and vacuums equipped with high-efficiency (HEPA) filters should be used to ensure that such emissions are contained and collected.

The Cohen Group has helped many clients resolve building water intrusion issues involving mold and restoration of building materials after drainage and sewer system back-ups. Please contact us if we can assist with your water-related concerns.