Mould Levels and Remediation Requirements

This is part 4 Of 5 part series.  (Yes, there is that much to say about mould!)


Mould is classified in three levels and each level has a specific set of procedures that must be followed in classifying and remediating.
Level 1:  Small-scale remediation, where impacted building material is less than 1 square meter.

Regular building maintenance staff can conduct the remediation. Workers should be properly trained to perform the mould abatement, be medically fit, clean-shaven and have proper immunization.

While performing work, workers should wear disposable coveralls, dust-impermeable gloves, half-face air-purifying respirator fitted with replaceable filters (N95 minimum) that meets the requirements of CSA Standard Z94.4 and eye protection.

The HVAC system should be turned off to the area and all immediate and adjacent systems should be sealed over. A drop sheet should be placed below the mouldy material when applicable. All waste should be placed in two 6-mil disposal bags. Upon removal, the area should be HEPA vacuumed.


Level 2:  Medium-scale remediation, where impacted building material is between 1 and 10 square meters.

Level 2 includes all items in the Level 1 along with the following requirements:

A competent supervisor must be present during the work. The area should be isolated with polyethylene sheeting and under negative pressure to a minimum of 0.02 inches of water column. 

Level 3:  Large-scale remediation, where impacted building material is greater than 10 square meters.

Level 3 remediation includes all items in the Level 2 along with the following requirements:

An experienced health and safety professional must be consulted prior to commencing the remediation. Workers should wear a full-faced air-purifying respirator fitted with P100 filters. The enclosure should include a decontamination facility for workers and a separate decontamination facility for waste. Upon completion, the Health and Safety Professional should inspect the work area and air samples collected.

As you can see a remediation contractor should be used for all of these procedures. In our next blog we will identify the category classifications of water damage.


If you have questions or would like to discuss your specific situation please contact us at Kenneth Homes Design Build Inc.


Upcoming Series On Everything To Know About Mould:

Part 5:  What Are The Categories Of Water Damage?


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