Mold Remediation in Occupied Homes (Research Report RR-0210)

Introduction The recommendations presented are based on the current NYC Health Department guidelines. The purpose of this document is to assist builders with the decisions regarding what to do and how to do it when mold is found in specific locations. The New York City guidelines are based on the area (number of square feet) that have mold on them. Unfortunately the area of involvement is often difficult to determine before removing sheathing or gypsum board. These recommendations are based on typical locations where moisture and mold occur in houses. Each case, however, is somewhat different, so proceed with caution and realize that the problem might be greater than anticipated. Four Steps for Responding to Mold Problems 1. Respond quickly with appropriate actions to stop water damage and limit potential exposure to occupants 2. Identify: • The cause of the moisture problem • The extent of contamination • The safety precautions for remediation 3. Implement remediation • Remove damaged material that cannot be effectively cleaned or that is more expensive to clean than replace. • Clean and salvage materials that are not severely damaged. • Dispose of the damaged material in an appropriate manner. Moldy materials can be sent to a regular landfill. Seal them in plastic bags to protect workers while the material is in transit. 4. Repair and replace removed materials incorporating the necessary changes to correct the underlying moisture problem. • Dry out the area being remediated before closing in a wall or ceiling. General Recommendations Carefully assess the problem before beginning the cleanup. If the moisture problem started in a closed cavity (wall, ceiling or floor), the mold that can be seen may be only a fraction of the mold present. Put another way, there may be a lot more mold in the wall than you think there is. Assume and prepare for the worst, while hoping for the best. Discuss the planned work with the owner and occupants. It is easier to address their concerns before you begin the work. Perform the work in a manner that minimizes the risk to the workers doing the remediation and the occupants of the building. Opening moldy wall cavities can release millions of mold spores and mold parts; inhaling these spores and body parts along with their associated toxins can potentially cause health problems. Make certain that the workers understand how to do the work and what they need to do to protect themselves and the occupants of the building.. Dispose of the damaged material in an appropriate manner. Moldy materials can be sent to a regular landfill. Sealing them in plastic bags protects workers while the material is in transit. Whenever possible remove moldy material through a window or door to minimize the chance that mold will be released into the rest of the building. Transporting moldy materials through clean areas should be minimized. Clean before you dry. Drying before cleaning can cause mold to become airborne. You do not have to kill mold in order to clean up mold. Cleaning up mold in essence means removing mold. Biocides can be more dangerous than the mold. Don’t use bleach; use soap and water. Bleach kills, but it does not clean (remove) the mold. In single family residential buildings it is often possible to pressurize the occupied portion of the building rather than to depressurize the work area. For example, if the problem is a moldy crawlspace, pressurize the upstairs using a fan door. Workers with appropriate personal protection can perform the work by entering through an exterior access, avoiding airlocks, protection of furnishings and passing contaminated material through the occupied space. If there is not an external access, make one. This makes the clean-up much simpler and safer. Attics, garages, basements and easily isolated additions can be treated this way. Special attention must be paid to any air ducts that are located in the contaminated area. Deciding Whether a Material Should be Replaced or Salvaged The general guidance is that soft, absorbent materials that contain a carbon source easily accessible to mold should be discarded unless there are compelling reasons to attempt to salvage them. Paper, textiles and paper covered gypsum board are examples of materials that should usually be discarded. If there is only a small amount of obviously superficial contamination, these materials may be cleaned (soap and water). If they have more than a few colonies, but are worth enough to salvage (e.g. books, art work, musical instruments, vintage carpets), they are worth enough that the salvage work should be performed by specialists. Materials like lumber, plywood, oriented strand board (OSB), particle board, paper covered gypsum board may or may not be salvageable. The base case test is - has the material lost structural integrity? Most mold species cannot degrade the cellulose-lignin cell wall of intact lumber (there are, of course, a few exceptions - stachybotrys and fusarium for example). So mold growing on solid lumber is most likely a surface contamination issue, not a structural issue. It can be cleaned, dried and salvaged.