Fighting Mold — The Homeowners' Guide from CMHC #3 in a series

How much mold is growing?

One way to know is to estimate the area of the mold.
Mold is considered to cover a "small area" if the patch is no larger than a square meter. There should be no more than three patches, each patch smaller than a square meter. Clean up small areas yourself using a detergent solution, household rubber gloves and a dust mask for protection. Refer to How to clean-up small problems for the procedure.
Small moldy areas in homes may become larger over time, if ignored, so it's important to clean up and remove even small patches of mold.
The mold area is considered "moderate" if there are more than three patches, each patch smaller than a square meter, or there is one or more isolated patches larger than a square meter but smaller than 3 square metres (size of a 4 x 8 foot sheet of plywood). Assessment by a professional is recommended. You can clean up moderate amounts of mold but you must follow the proper procedures and use the proper protective equipment. Refer to Moderate area clean-up for the procedure.
A mold area is considered "extensive" if a single patch of mold is larger in area than a sheet of plywood. Being exposed to this much mold is not a good idea. Do not attempt to clean up large areas of mold yourself. You need professional help to determine why the mold is there in the first place and how to clean it up.
When should you seek professional help?

You may need professional help when:

• There is a lot of mold
• The home is very damp and moist
• Mold comes back after repeated cleaning
• A family member suffers from asthma or respiratory problems or other health problems that appear to be aggravated inside the home

How do you get professional help?

Contact your IAC2 Certified Inspector Website for a list of individuals who have completed the Residential Indoor Air Quality Investigator program. A trained IAQ investigator, who operates a private business and sells his/her services, examines the indoor air quality of your home and documents your concerns. He/she identifies the problems, finds their sources and suggests solutions in a written report. Recommendations are provided to you in an action plan that consists of various options to improve the indoor air quality in your home.
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