Mold: Tackling Contamination in Buildings
Molds can become a problem in any building, in any climate and in any geographic area of the country. If water or moisture problems are not promptly and appropriately attended to, molds and other microbes can begin to grow. These microorganisms can feed on a variety of building materials including wood, paper, paint, adhesives and backing materials. Before the growth of molds becomes visible, there will be a faint musty or earthy smell. In time, the molds may appear on the outside of the wall as a stain or discoloration.
These problems can be prevented by performing regularly scheduled building inspections and routine maintenance such as:
Watching for condensation or areas of dampness, then controlling the moisture problem
Preventing condensation problems by using exhaust fans
- Venting moisture generating appliances to the outside
Not letting foundations stay wet
- Providing appropriate drainage
- Inspecting crawlspaces for standing water
- Cleaning out gutters
- Maintaining grade so that moisture flows away from the building
Performing preventative maintenance as scheduled
- Periodically checking for roof damage, especially after storms
- Maintaining gutters and downspouts
- Checking flat roofs for pooling of water and solving the drainage problem.
- Checking HVAC systems for leakage and keeping drip pans clean and dry.
If a moisture problem does develop, then promptly dry the wet or damp building materials. If water damage occurs as a result of a flow of water, then follow the procedures outlined in the IICRC (Institute of Inspection, Cleaning and Restoration Certification) S500 (Second Edition) Standard and Reference Guide for Professional Water Damage Restoration.
The American Conference of Governmental Industrial Hygienists (ACGIH) states, in their publication Bioaerosols: Assessment and Control, that “growth that has occurred in a surface layer of condensation on painted walls or nonporous surfaces (including wood) can usually be removed by (a) vacuuming by using equipment with high-efficiency filters or direct air exhaust to the outdoors, (b) washing with a dilute solution of biocide or a mild detergent, or (c) cleaning, thorough drying and repainting.”In other words, molds that grow as a result of condensation on the surface of a wall, where the wallboard is not wet except on the surface, can be cleaned by the methods stated in the previous paragraph. However, porous building materials, such as drywall, that have become wet and have visible mold growth should be replaced.
Where wall cavities or other concealed areas of the building have been wet for more than 72 hours, an investigation of the affected area must be performed to establish whether or not there has been an amplification of mold. In conducting this investigation, care must be taken to insure that the indoor environment does not become contaminated. Precautions should be taken to minimize cross contamination from affected to unaffected areas. It’s recommended that contaminated areas be contained with polyethylene sheeting, often in combination with negative air pressure, to prevent cross contamination. In some cases, it may be necessary to shut down air handling equipment and seal off supply and return registers.
If visible mold is found growing on building system components or other less permeable surfaces, then it should be removed by HEPA (High Efficiency Particulate Air) vacuuming if dry; by physical removal from the surface while HEPA vacuuming; or by removing and replacing the affected building material. Other areas that have been contaminated with settled spores may be cleaned using an appropriate method for that material.
The IICRC S500 makes the following comment: “When visible microbial growth has occurred in a structure, mold remediation practices must be properly employed to address the situation, and containment procedures may be necessary to prevent spreading spores to uncontaminated areas. Remediation requires (a) removing porous materials exhibiting extensive microbial growth, (b) physically removing surface microbial growth on non-porous materials (including wood) to typical background levels, (c) the removal of settled spores, and (d) reducing moisture to levels that do not support microbial growth. The American Conference of Governmental Industrial Hygienists (ACGIH) further states that the ‘Effective remediation of water–damaged or microbially contaminated buildings involves (a) the use of appropriate techniques to promote rapid drying, and (b) complete removal of contaminated materials rather than the application of biocides without these steps’ (ACGIH Bioaerosols: Assessment and Control - publication #3180).”
Cleaners and restorers that perform mold remediation services must wear the appropriate personal protection equipment as required by OSHA or any other governmental agency having authority over such work.
The emergence of mold and sewage damage remediation (or cleanup) technology is relatively new. There are very few guidelines available to the general public or the professional water damage restorer. An environmental consultant experienced with water-damaged buildings and microbial contamination issues should evaluate all buildings that need to be or have been remediated.
It’s highly recommended that technicians consult with knowledgeable indoor environmental experts who may include indoor environmental (IE) consultants, industrial hygienists (IHs) or environmental health professionals (EHPs).”
Note: This article does not take into consideration all the procedures that may be required in a restorative drying or mold remediation project