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ORF Home > Technical Resources > Policies and Rules > Guidance on Moisture Infiltration after 48 Hours

Guidance on Moisture Infiltration after 48 Hours

When water infiltration has remained untreated after 48 hours, mold growth may have begun, and there may be visible evidence of growth or a moldy, damp smell. In these cases, the situation is now one of potential mold remediation, and the building occupant must contact the ORS Division of Occupational Health and Safety (DOHS) at 301-496-3353. The guidance provided here is for information purposes only and is not a substitute for DOHS expertise.

Remediation efforts are more intensive than prevention, and they must be designed to protect the health of building occupants and remediation personnel. Recommendations for cleanup or remediation by DOHS will depend on the extent of the damage, the types of materials affected, and the presence/type of mold growth. DOHS will make recommendations on whether current occupants should be relocated; on the containment/cleanup methods to be used (including whether remediation can be done by in-house personnel or if professionals are required); and on the types of personal protective equipment required by clean-up crews.

Air handlers (AHUs) servicing the affected area(s) should not be shut down unless gross, visible mold growth has been identified and a containment area cannot be established. A containment area is created by covering the supply and return air openings with 6-mil thick plastic. Having the AHU running helps to expedite the drying process.

Water Stains: Water stains are commonly found in buildings throughout the NIH campus. The following procedures should be followed:

If the stain is dry:

  • Carpet: Have the stain cleaned. If it goes away and then comes back, identify and eliminate the moisture infiltration source and replace the carpet.
  • Wallboard: Use a moisture meter to check for moisture behind the wall. To use a moisture meter, check the affected area and compare the reading to the reading in a non-affected control area. If excessive moisture (higher than adjacent walls) is detected, replace the wallboard. If no moisture is detected, clean and paint the wallboard.
  • Ceiling tile: Discard and replace.

If the stain is still wet:

  • Carpet or Wallboard: Fix the moisture problem and dry and clean the affected area.
  • Ceiling tiles: Discard and replace.

Mechanical Rooms: Mechanical room leaks, standing water, consistent humidity levels above 60%, and condensation problems should be fixed as soon as they are detected. If standing water is found in areas that have concrete or tile floors and there is no apparent mold, the DOHS does not need to be contacted.

Contaminated Water: If the water infiltrating a building area is polluted, the DOHS should be contacted immediately. Potable, de-ionized (DI), reverse osmosis (RO), and distilled water are considered unpolluted unless they have come in contact with a pollution source. All others are considered polluted. Following repairs to prevent any further infiltration, any contaminated ceiling tiles, carpet, upholstered furniture, paper products, or similar materials must be disposed of in sealed containers by personnel wearing appropriate personal protective equipment (protective clothing, gloves, boots, and, at a minimum, a N-95 type respirator). The entire area must be disinfected.

Moisture Meters: A moisture meter may be useful in the following situations:

  • When a dried stain has been found on wallboard and a decision must be made as to whether the stain can be cleaned or further action is required.
  • To determine if wallboard has been sufficiently dried during the 24-48 hour period. Sometimes it is difficult to determine when wallboard has been completely dried. In these cases, use a moisture meter to check drywall in an affected area and compare the reading to a control reading in a non-affected area. Readings should be the same.

Biocides: The goal of mold remediation is to remove the mold and prevent human exposure and damage to building materials and furnishings. Remediation should clean up mold contamination, not just kill it. Even after it is dead, the remaining mold fragments are still allergenic, and some are potentially toxic. The use of biocides is not routinely recommended during remediation. However, there may be some instances when the use of a biocide may be justified, such as when immune compromised individuals are present. It is not possible to get rid of all mold spores in a building environment. Spores will be present, but they will not grow if the moisture problem in the building is fixed.

Biocides are toxic to humans as well as molds. If biocides are used, occupants must be evacuated from the area, and the area must be properly ventilated. Remediation personnel must wear appropriate personal protective equipment. Since some biocides are registered with the EPA as pesticides, these may only be applied by licensed Federal or State Applicators.

Mold Sampling: In most cases, sampling for mold is unnecessary even if there are visible signs of mold or moldy, musty odors. In some specific instances such as where litigation is involved, the source of the mold is unclear, or health concerns are a problem, then sampling may be part of the site evaluation. Sampling for mold should only be done after a sampling strategy has been developed. Since no EPA or other Federal Threshold limits have been set for mold or mold spores, sampling cannot be used to check a building’s compliance with existing standards.

This page was last updated on Nov 27, 2012