The most important step in solving a mold problem is to identify and correct the moisture sources that
allowed the growth in the first place. Common indoor moisture sources include:
- Flooding
- Condensation - indoor humidity that is too high or surfaces that are too cold
- Roof leaks
- Plumbing leaks
- Humidifier use
- Firewood stored indoors
- Line drying laundry indoors
- Overflow from tubs, sinks, or toilets
- Improper venting of combustion appliances
- Movement through basement walls and slab
- Inadequate venting of kitchen and bath humidity
- Failure to vent clothes dryer exhaust outdoors - including electric dryers
- House plants - watering them can generate large amounts of moisture
To keep indoor surfaces as dry as possible, try to maintain the home's relative humidity between 20-40
percent in the winter and less than 60 percent the rest of the year. You can purchase devices to
measure relative humidity at some home supply stores. Ventilation, air circulation near cold surfaces,
dehumidification, and efforts to minimize the production of moisture in the home are all very
important in controlling high humidity that frequently causes mold growth in our cold climate.
As soon as possible, begin drying any materials that are wet. For severe moisture problems, use fans
and dehumidifiers and move wet items away from walls and off floors. Check with equipment rental
companies or restoration firms to see if you can rent fans and dehumidifiers.
Items which have absorbed moisture (porous materials) and which have mold growing on them need to be
removed, bagged and thrown out. Such materials may include sheet rock, insulation, plaster,
carpet/carpet pad, ceiling tiles, wood products (other than solid wood), and paper products. Likewise,
any such porous materials that have contacted sewage should also be bagged and thrown away. Non-porous
materials with surface mold growth may be saved if they are cleaned well and kept dry.
Surface mold growing on non-porous materials such as hard plastic, concrete, glass, metal, and solid
wood can usually be cleaned. Cleaning must remove and capture the mold contamination, because dead
spores and mold particles still cause health problems if they are left in place.
- Thoroughly scrub all contaminated surfaces using a stiff
brush, hot water and a non-ammonia soap/detergent or commercial cleaner
- Collect excess cleaning liquid with a wet/dry vacuum, mop
or sponge
- Rinse area with clean water and collect excess rinse
water
After cleaning has removed all visible mold and other soiling from contaminated surfaces, a
disinfectant may be used to kill mold missed by the cleaning. In the case of sewage contamination,
disinfection must be performed. Contact your home inspector for advice.
- Mix 1/4 to 1/2 cup bleach per gallon of water and apply
to surfaces where mold growth was visible before cleaning. The solution can be applied with a
spray bottle, garden sprayer, it can be sponged on, or applied by other methods.
- Collect any run-off of bleach solution with a wet/ dry
vacuum, sponge or mop. However, do not rinse or wipe the bleach solution off the areas being
treated -- allow it to dry on the surface.
Continue looking for signs of moisture problems or return of mold growth. Be particularly alert to
moisture in areas of past growth. If mold returns, repeat cleaning steps and consider using a stronger
solution to disinfect the area again. Regrowth may signal that the material should be removed or that
moisture is not yet controlled.