Fighting Mold — The Homeowners' Guide from CMHC #4

How to clean up mold problems

• "Small areas" of mold can be cleaned with a detergent solution.
• Wear a mask, safety goggles and rubber gloves.
• Seek professional help if there is a lot of mold or if mold comes back after cleaning.

Bleach is NOT recommended

The presence of organic (humic) materials, the pH (acidity/alkalinity) of the water, the surface material and contact time affect the effectiveness of bleach for disinfection. Since these factors are not generally controlled, bleach cannot be relied upon for disinfection. The most compelling reason for advising against bleach is that fumes are harmful but in addition, overuse of bleach will result in increased releases of chlorinated effluents which can be harmful to the environment.
"Small area" clean-up

You can clean up "small areas" of mold (fewer than three patches, each smaller than a square meter) yourself. The minimum protective wear needed are:

• safety glasses or goggles;
• a disposable dust mask (3M 8210 or equivalent); and
• household rubber gloves.

Infants and other family members with asthma, allergies or other health problems should not be in the work area or adjacent room during the cleaning.
Washable surfaces:

Scrub with an unscented detergent solution; then sponge with a clean, wet rag and dry quickly.
Using an unscented detergent will make it easier for you to detect residual moldy odours.
Moldy drywall:

Clean the surface with a damp rag using baking soda or a bit of detergent. Do not allow the drywall to get too wet.
Mold that comes back after cleaning is usually an indication that a source of moisture has not been removed. Seek professional help from a trained IAQ investigator.
"Moderate area" clean-up

• Clean "moderate areas" of mold, but wear proper protective equipment and follow precautions.
• Seek professional help if there is a lot of mold or if mold comes back after cleaning.

If you follow the proper procedures and use the proper protective equipment, you can clean up "moderate areas" of mold. "Moderate" means more than 3 patches of mold, each smaller than one square meter, or one or more isolated patches larger than one square meter but smaller than 3 square meters (size of a 4 x 8 foot sheet of plywood).
Safety precautions

• Wear a disposable dust mask (for example, 3M 8210 or equivalent), glasses or safety goggles and household rubber gloves.
• Isolate the area to be cleaned with plastic sheeting, taped to walls and ceiling.
• Infants and other family members suffering from asthma, allergies or other health problems should not be in the work area or adjacent room during the cleaning.

A small clean up should take minutes (not hours) to finish. When the clean up takes hours to a day to finish, it is suggested that you upgrade to a better filter, such as a half-face respirator with charcoal cartridges. An exhaust fan installed in a window in the room being cleaned would prevent contamination of other areas of the house as well as provide ventilation.
General cleaning

Vacuum surfaces with a vacuum cleaner which has a High Efficiency Particulate Air (HEPA) filter or is externally exhausted. Scrub or brush the moldy area with a mild unscented detergent solution. Rinse by sponging with a clean, wet rag. Repeat. Dry quickly. HEPA vacuum the surfaces that were cleaned as well as surrounding areas.
Cleaning wood surfaces

Vacuum loose mold from wood surfaces using a HEPA or externally exhausted vacuum. Try cleaning the surface of the wood with detergent and water. Rinse with a clean, damp rag and dry quickly. If the staining does not come off, sand and vacuum the surface of the wood with a vacuum/sander combination. It is important to vacuum at the same time to prevent mold spores from being dispersed into the air. Note that wood affected by rot may need to be replaced.
Cleaning concrete surfaces

Vacuum the concrete surfaces to be cleaned with a HEPA or externally exhausted vacuum cleaner. Clean up surfaces with detergent and water. If the surfaces are still visibly moldy, use TSP (trisodium phosphate). Dissolve one cup of TSP in two gallons of warm water. Stir for two minutes. Note: TSP must not be allowed to come in contact with skin or eyes. Saturate the moldy concrete surface with the TSP solution using a sponge or rag. Keep the surface wetted for at least 15 minutes. Rinse the concrete surface twice with clean water. Dry thoroughly, as quickly as possible.
Moldy drywall

The paper facings of gypsum wallboard (drywall) grow mold when they get wet or repeatedly wet and don't dry quickly. Cleaning with water containing detergent not only add moisture to the paper but also can eventually damage the facing. If the mold is located only on top of the painted surface, remove it by general cleaning (see above). If the mold is underneath the paint, the moldy patch and other moldy material behind it are best cut out and the surrounding areas also cleaned. This should be done by a mold clean-up contractor. New materials may become moldy if the moisture entry has not been stopped. If this is the case, replacement of the materials should be deferred until the source of the moisture is corrected. The affected areas should be temporarily covered with plastic sheeting and sealed at the edges.
Any areas that show new patches of mold should be cleaned promptly.
Dealing with an ongoing problem

Repair to the building envelope is required if moisture is entering the home from the outside. At the same time, steps should be taken inside the home to reduce the occupants' exposure to mold.
Step 1 - Discard moldy or damaged materials

Wear a dust mask and gloves. Furnishings, such as mattresses, carpets, or sofas that got wet or have been stored in damp conditions should be discarded. Discard items that are no longer needed. Use this opportunity to reduce the amount of furnishings - this means fewer materials to absorb moisture and grow mold. Clothes and other items that have been cleaned should be stored in sealed plastic bags to prevent re-contamination.
Step 2 - Vacuum

Proper vacuuming reduces the amount of mold spores. All surfaces in the home (floors, walls, ceilings, shelves) and non-washable furnishings (such as sofas, chairs, etc.) must be vacuumed thoroughly.
Step 3 - Prevent

Keep moisture generated within the home to a minimum by conscientiously following the prevention steps presented in the next section.
Step 4 - Clear wet areas

Pull carpets and furnishings away from walls that get wet. Carpets and underpads that are moldy should be cut out and discarded.
Step 5 - Dry

Take steps to dry up areas that get wet. Monitor the relative humidity of the air. Use a portable dehumidifier, if necessary. Ensure that the condensate drain pan of the dehumidifier is emptied regularly.
Step 6 - Isolate

If the mold is limited to one area, isolate the area if possible. Cover the affected surfaces with plastic sheeting secured at the edges with duct tape. Note that this is only a temporary measure to minimize your exposure.
Step 7 - Clean

Healthy individuals can regularly clean "small" and "moderate" areas of mold, thus preventing these from getting out of hand, by following the safety precautions and cleaning guidelines.
Step 8 - Seek professional help

Consider seeking professional help from trained IAQ investigators to identify appropriate remediation steps inside the home. Removing large amounts of mold will require the services of mold clean-up contractors.
Preventing mold

• Keep the home dry.
• Find and fix water leaks.
• Discard clutter and excess stored materials.
• Clean and maintain the home regularly.
• Encourage lifestyle practices that reduce moisture.