Learn About Mold Damage

Mold: Prevention, Remediation & Containment

Concern about indoor exposure to mold has been increasing as the public becomes aware that exposure to mold can cause a variety of health effects and symptoms. Mold has the potential to cause health problems such as allergic reactions sneezing, runny nose, red eyes, and skin rash. It can also irritate the eyes, skin, nose, throat, and lungs. Remediation of mold and moisture problems including measures designed to protect the health of building occupants.

Mold can be found almost anywhere and can grow on virtually any organic substance, as long as moisture and oxygen are present. When excessive moisture accumulates in buildings, mold growth will often occur if the moisture problem remains undiscovered or unaddressed. It is impossible to eliminate all mold spores in the indoor environment, but mold can be controlled.

Moisture problems can have many causes, including uncontrolled humidity. Changes in building construction practices from the 1970s to 90s have been linked to increased mold growth. Buildings that are tightly sealed often lack adequate ventilation, potentially leading to moisture buildup. Building materials, such as drywall, may not allow moisture to escape easily.

Mold Accumulation Prevention

  • Clean and dry wet or damp spots within 48 hours.
  • Fix leaky plumbing and leaks in the building envelope as soon as possible.
  • Don't let foundations stay wet. Provide drainage and slope the ground away from the foundation.
  • Watch for condensation and wet spots. Fix sources of moisture problems as soon as possible.
  • Perform regular building/HVAC inspections and maintenance as scheduled.
  • Prevent moisture due to condensation by increasing surface temperature or reducing the moisture level in air (humidity). To increase surface temperature, insulate or increase air circulation. To reduce the moisture level in air, repair leaks, increase ventilation (if outside air is cold and dry), or dehumidify (if outdoor air is warm and humid).
  • Keep heating, ventilation, and air conditioning (HVAC) drip pans clean, flowing properly, and unobstructed.
  • Vent moisture-generating appliances, such as dryers, to the outside where possible.
  • Maintain low indoor humidity, below 60% relative humidity (RH), ideally 30-50%, if possible.

Unseen Mold

Mold may be growing on hidden surfaces, such as the backside of dry wall, wallpaper, the top of ceiling tiles, the underside of carpets and pads, etc. Building materials may act as vapor barriers, trapping moisture underneath their surfaces and thereby providing a moist environment where mold can grow. If a building smells moldy, you may suspect hidden mold or if you know there has been water damage and building occupants are reporting health problems. Investigating hidden mold problems may be difficult and will require caution when the investigation involves disturbing potential sites of mold growth. Removal of wallpaper can lead to a massive release of spores from mold growing on the underside of the paper.

Remediation Plan

Remediation activities should be scheduled during off-hours when building occupants are less likely to be affected, if possible. In the decision to relocate a buildings occupants, one should consider the size of the area affected, the extent of health effects reported by the occupants, the potential health risks associated with debris, and the disruption likely to be caused by remediation activities.


  1. Fix the water or humidity problem. Complete and carry out repair plan if appropriate. Revise and carry out maintenance plan if necessary. Revise remediation plan as necessary, if more damage is discovered during remediation.
  2. Completely clean up mold and dry water-damaged areas. Select appropriate cleaning and drying methods for damaged/ contaminated materials. Carefully contain and remove moldy building materials. Use appropriate Personal Protective Equipment (PPE). Arrange for outside professional support if necessary. Continue to communicate with building occupants, as appropriate to the situation. Be sure to address all concerns.

Cleanup Methods

A variety of mold cleanup methods are available for remediating damage to building materials and furnishings caused by moisture and mold growth. The specific method or group of methods used will depend on the type of material affected. Please note that professional remediators may use some methods not covered in these guidelines.

Method 1: Wet Vacuum

Wet vacuums are vacuum cleaners designed to collect water. They can be used to remove water from floors, carpets, and hard surfaces where water has accumulated. They should not be used to vacuum porous materials, such as gypsum board. They should be used only when materials are still wet-wet vacuums may spread spores if sufficient liquid is not present.

Method 2: Damp Wipe

Some molds may be toxic. Whether dead or alive, mold is allergenic. Mold can generally be removed from nonporous surfaces by wiping or scrubbing with water, or water and detergent, but dry these surfaces quickly and thoroughly to discourage further mold growth. Porous materials that are wet and have mold growing on them may have to be discarded, becaue mold can be difficult or impossible to remove completely from such materials.

Method 3: HEPA Vacuum

High-Efficiency Particulate Air vacuums are recommended for final cleanup of remediation areas after materials have been thoroughly dried and contaminated materials removed. HEPA vacuums are also recommended for cleanup of dust that may have settled on surfaces outside the remediation area. When changing the vacuum filter, remediators should wear PPE to prevent exposure to the mold that has been captured.

Method 4: Discard

Remove Damaged Materials and Seal in Plastic Bags

Materials that are contaminated with mold growth and are not salvageable can usually be discarded as ordinary construction waste. It is important to package mold contaminated materials in sealed bags before removal from the containment area to minimize the dispersion of mold spores throughout the building. Items that have heavy mold growth should be covered with polyethylene sheeting and sealed with duct tape before they are removed from the containment area.

Always use gloves and eye protection when cleaning up mold!

Personal Protective Equipment (PPE)

Remediation job disturb mold and mold spores become airborne. Actions that are likely to stir up mold include: invasive procedures used to examine or remediate mold growth in a wall cavity; breakup of moldy porous materials; actively stripping or peeling wallpaper; and using fans to dry items.

The primary function of Personal Protective Equipment (PPE) is to avoid inhaling mold and mold spores and to avoid mold contact with the skin or eyes.

Skin and Eye Protection

Gloves are required to protect the skin from contact with mold allergens (and in some cases mold toxins) and from potentially irritating cleaning solutions. The glove material should be selected based on the type of materials being handled. If you are using a biocide, such as chlorine bleach or a strong cleaning solution, select gloves made from natural rubber, neoprene, nitrile, polyurethane,or PVC. If you are using a mild detergent or plain water, ordinary household rubber gloves may be used. To protect your eyes, use properly fitted goggles or a full-face respirator with HEPA filter. Goggles must be designed to prevent the entry of dust and small particles. Safety glasses or goggles with open vent holes are not acceptable.

Respiratory Protection

Respirators protect cleanup workers from inhaling airborne mold, mold spores, and dust.

Minimum : Use an N-95 respirator when cleaning up a small area affected by mold. This device covers the nose and mouth and will filter out 95% of the particulates in the air.

Limited : Use of a half-face or full-face air purifying respirator (APR) equipped with a HEPA filter cartridge. These respirators contain both inhalation and exhalation valves that filter the air and ensure that it is free of mold particles. The HEPA filters do not remove vapors or gases. Always use respirators approved by the National Institute for Occupational Safety and Health.

Full : In situations in which high levels of airborne dust or mold spores are likely or when intense or long-term exposures are expected , a full-face, powered air purifying respirator (PAPR) is recommended. Full-face PAPRs use a blower to force air through a HEPA filter. Individuals must be trained to use their respirators before they begin remediation.

Disposable Protective Clothing

Disposable clothing is recommended during a medium or large remediation project to prevent the transfer and spread of mold to clothing and to eliminate skin contact with mold.


The purpose of containment during remediation activities is to limit release of mold into the air and surroundings. Mold and moldy debris should not be allowed to spread to areas in the building beyond the contaminated site.

Limited Containment

Limited containment is generally recommended for areas involving between 10 and 100 square feet (ft 2 ) of mold contamination. The enclosure around the moldy area should consist of a single layer of 6- mil, fire-retardant polyethylene sheeting. The containment should have a slit entry and covering flap on the outside of the containment area.

For small areas, the polyethylene sheeting can be affixed to floors and ceilings with duct tape.

For larger areas, a steel or wooden stud frame can be erected and polyethylene sheeting attached to it.

Full Containment

Full containment is recommended for the cleanup of mold contaminated surface areas greater than 100 ft or in any situation in which it appears likely that the occupant space would be further contaminated without full containment. Double layers of polyethylene should be used to create a barrier between the moldy area and other parts of the building. A decontamination chamber or airlock should be constructed for entry into and exit from the remediation area. The entryways to the airlock from the outside and from the airlock to the main containment area should consist of a slit entry with covering flaps on the outside surface of each slit entry. The chamber should be large enough to hold a waste container and allow a person to put on and remove PPE. All contaminated PPE, except respirators, should be placed in a sealed bag while in this chamber.

Respirators should be worn until remediators are outside the decontamination chamber. PPE must be worn throughout the final stages of HEPA vacuuming and damp-wiping of the contained area. PPE must also be worn during HEPA vacuum filter changes or cleanup of the HEPA vacuum.

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