October 2008
Getting rid of mold
Once you've found the source of moisture and mold, use plastic sheeting to contain and prevent mold spores from spreading
throughout the house. If the mold covers less than 10 square feet, you may be able to eliminate the problem yourself. But
you'll need to hire a professional mold remediator (See Finding a pro) for larger areas if you or a family member is highly allergic, if your ventilation system is contaminated, or if contaminated
water is involved.
Many of the steps are the same no matter who does the job:
Eliminate the source
Remove the mold
Keep mold from coming back
For information on federal guidelines for mold remediation in schools and public buildings, which may be adapted for home
use, see EPA publication 402-K-01-001, March 2001, or go to www.epa.gov/mold/mold_remediation.html. You can also type the publication number in the search box on the EPA Web site to access it.
Many of the steps are the same no matter who does the job:
Eliminate the source
- Repair leaky roofs, poor or missing chimney and window flashing, missing or damaged shingles or siding, and leaky pipes.
- Repair or replace damaged gutters and leaders.
- For mold caused by exterior flooding, evaluate the foundation and grading of your home to make sure that land is sloped away
from the foundation of your house.
Proper way to wear an N-95 respirator.
Photos from National Centers for Disease Control & Prevention- Begin by protecting yourself with an N-95 disposable respirator approved by the National Institute of Occupational Safety
and Health; goggles; and heavy-duty rubber, neoprene, or PVC gloves. Packages of N-95 respirators cost about $12 to $25 and
are available in hardware and building-supply stores, by mail, and online. Make sure the respirator is fitted properly.
- Bag and discard any carpet, ceiling tiles, wallboard, paper, insulation, or other porous materials that have been wet for
48 hours or more. They promote mold growth even if they aren't visibly contaminated.
- Scrub other materials with a strong solution of detergent and water or 1 cup of chlorine bleach per 5 gallons of water. Wear
plastic or rubber gloves and eye protection. Warning: Never mix bleach with any other cleaning solution, especially ammonia,
which creates a poisonous gas. Avoid biocides other than chlorine bleach, which can trigger allergic reactions. These biocides
usually aren't recommended for home use by nonprofessionals, and they are federally regulated for specific uses when applied
by professionals.
- Wood studs and exposed joists may have to be wire-scrubbed with bleach, sanded, and dried out before reinstalling wallboard
and flooring.
- Allow all surfaces to thoroughly air-dry.
- Vacuum up debris and particles using a wet-dry shop vac with a HEPA filter.
- Decontaminate clothing by washing it in hot water with detergent. Bag in plastic and discard all used masks and dirty materials.
- Install outside-venting exhaust fans in bathrooms and dehumidifiers in basements to keep relative indoor humidity levels between
30 and 50 percent. You can measure relative humidity using a hygrometer (about $10 to $50 at hardware stores).
- Don't use wallpaper or carpets in bathrooms and other damp areas.
- Leave flood-prone basements unfinished, since finished basements can be more susceptible to mold problems, according to the
2004 Damp Indoor Environments study conducted by the National Academy of Sciences Institute of Medicine.
- Don't bother with mold test kits. In theory, these kits should be able to confirm that you or the remediator has truly cleaned
up the mold. Unfortunately, our tests of four common kits found they can't be relied on. When we sent six unused petri dishes
back to the companies for testing--like you might after cleaning up mold--three of the reports came back saying we did have
mold, suggesting they might have been unintentionally contaminated at some point. To learn about the other problems we found,
see mold test kits.
DUCTS: A SPECIAL CONCERN
Don't even think about cleaning out contaminated heating, ventilation, or air-conditioning (HVAC) systems yourself. Manufacturers recommend that furnaces, boilers, water heaters, heat pumps, and central air conditioners that have been submerged under flood waters be replaced. Water damage could cause combustion or electrical-system malfunctions that could be life-threatening. And, the duct-distribution system connected to that equipment also needs to be cleaned and disinfected.
A qualified mold-remediation contractor (See Finding a pro) must clean the entire system from supply to return, not just the ductwork, to prevent spreading mold spores throughout the house. It also involves vacuuming and scrubbing out the system under containment, then applying EPA-approved chemicals to reduce germs and fungi.
Work should be performed according to ACR 2005, the industry standard for assessment, cleaning, and restoration of HVAC systems developed by the National Air Duct Cleaners Association (NADCA). Unless an inspection shows it is mechanically sound, fiberglass or other porous ductwork typically must be discarded because it cannot be cleaned with biocides. For more information on cleaning fiberglass ductwork (and also insulation), contact the North American Insulation Manufacturers Association (NAIMA) at www.naima.org. See EPA document number 402-K-97-002, October 1997, or www.epa.gov/iaq/pubs/airduct.html for more information. You can also type the publication number into the search box on the EPA Web site to access it.
The national average for routine duct cleaning is $450 for a 2,000 square-foot house, though what you pay can vary widely based on the size and complexity of the job, says John Schulte, a spokesman for NADCA, in Washington, D.C. Figure on roughly eight hours with a two-man crew. Replacing flexible duct sections, washing metal ducts, or removing or replacing fiberglass insulation will increase costs and the time needed to complete the job.
For more information on duct cleaning and to find an assiciation member in your area, go to www.nadca.com.
Don't even think about cleaning out contaminated heating, ventilation, or air-conditioning (HVAC) systems yourself. Manufacturers recommend that furnaces, boilers, water heaters, heat pumps, and central air conditioners that have been submerged under flood waters be replaced. Water damage could cause combustion or electrical-system malfunctions that could be life-threatening. And, the duct-distribution system connected to that equipment also needs to be cleaned and disinfected.
A qualified mold-remediation contractor (See Finding a pro) must clean the entire system from supply to return, not just the ductwork, to prevent spreading mold spores throughout the house. It also involves vacuuming and scrubbing out the system under containment, then applying EPA-approved chemicals to reduce germs and fungi.
Work should be performed according to ACR 2005, the industry standard for assessment, cleaning, and restoration of HVAC systems developed by the National Air Duct Cleaners Association (NADCA). Unless an inspection shows it is mechanically sound, fiberglass or other porous ductwork typically must be discarded because it cannot be cleaned with biocides. For more information on cleaning fiberglass ductwork (and also insulation), contact the North American Insulation Manufacturers Association (NAIMA) at www.naima.org. See EPA document number 402-K-97-002, October 1997, or www.epa.gov/iaq/pubs/airduct.html for more information. You can also type the publication number into the search box on the EPA Web site to access it.
The national average for routine duct cleaning is $450 for a 2,000 square-foot house, though what you pay can vary widely based on the size and complexity of the job, says John Schulte, a spokesman for NADCA, in Washington, D.C. Figure on roughly eight hours with a two-man crew. Replacing flexible duct sections, washing metal ducts, or removing or replacing fiberglass insulation will increase costs and the time needed to complete the job.
For more information on duct cleaning and to find an assiciation member in your area, go to www.nadca.com.
