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Mould Remediation

Three Conditions must be met in order for microbial growth (including mould) to occur:

active attic mould

1. Temperature Range compatible with life. Simply put, if humans can survive in the temperature range, mould can and will thrive.

2. Organic Food Source present. Any organic material, that is one that is living or once was living is sufficient to support microbial growth. Drywall, OSB Sheeting, paper, cardboard, and even adhered dust debris are all commonly found viable food sources for mould to grow.

3. High Moisture Content. Moisture content measured directly within affected materials must exceed 35% for more than 24-48 hours for mould to grow. Humidity which exceeds 60% will, given sufficient time, support microbial growth.

If one of the Conditions Required for Microbial Growth are absent, growth will not occur. If one of the Conditions is disrupted, active mould growth will cease.

In Ontario, there are no formal legal regulations (such as Ontario 278/05 for Asbestos) which specify methodology for remediation, however the commonly adopted informal guideline followed by most restoration contractors is the Canadian Construction Association Guideline for Mould Remediation. While every remediation project is different, the steps to a successful remediation remain consistent.

1. Inspection
May include: bulk and/or air sampling, measurement of conditions & factors within building envelope, identification sources of 3 conditions required for growth.

2. Definition of Scope of Work.
In many circumstances, this is the step where contractors most often make the mistake. Incorrectly setting the scope of work means either they remove too little (and you still have unhealthy conditions present after remediation) or they remove too much material (making your costs of remediation and re-instatement higher). The only one who can possibly benefit by removing too much material is the contractor; more remediation equals more profit. I have encountered many a contractor who, when I've been called in to verify their recommedations, have tried to justify the scope being expanded without measured evidence by saying "better safe than sorry". While this may apply when handing firearms, this is just an attempt to assign a benefit to the customer for the contractor's incompetance. Even if performing a simple remediation yourself, paying a professional to set the required scope of work correctly is more than worth the expense.

3. Isolation.
The first and most important step when it comes to prevention of cross-contamination and customer safety. Isolation includes creation of a containment structure kept under negative pressure with HEPA-filtered Negative Air Machines. Simply stated, all air leaving the containment must first be HEPA-filtered to remove 99.97% of all particles .3 micron in size (or greater).

4. Removal of Material.
C.C.A. Guidelines dictate removing contaminated building material at minimum, 2 feet past visible growth.

5. HEPA-Vacuuming.
All surfaces within the containment must first be vacuumed with a HEPA-filter equipped vacuum after removal of material, then scrubbed with a purpose approved anti-microbial cleaner, before finally being re-vacuumed to remove settled spore contamination.

6. Air-Scrubbing.
During the process of remediation, mould spores become dislodged and airborne. HEPA-filtered Negative Air Machines similar to the ones utilized to create negative pressure aare utilized within the containment to trap airborne contamination. Duration of scrubbing required varies from project to project but, at minimum must be performed for a minimum of 24 hours prior to collection of post remediation air sampling.

There are a number of contractors who specify the use of an "Antimicrobial Treatment" after remediation to "minimize the potential for future growth" however if the conditions required for microbial growth occur, no treatment in my experience is 100% effective. It is up to each customer to determine what potential peace of mind, placebo variety or not, is worth but, in many circumstances you would be just as effective waving your chequebook over the treament site as allowing your contractor to spray chemicals which "prevent growth". Unfortunately, if the 3 conditions required to support microbial growth are present, a chemical that is superficially sprayed on the surface of an organic material will have limited efficacy.

Attic Mould

The discovery of attic mould often occurs during a home inspection prompted by the buying or selling of a property. Generally, most home owners don't spend much time in their attic, monitoring conditions and as a result, growth is typically well established by the time an issue is identified. Remediation of microbial growth located in attics typically includes removal of insulation, due to contamination from the distribution of spores from the normal mould reproductive process. While fiberglass insulation is not organic and therefore not a viable food source directly, spore contamination that will accumulate on the insulation surface will make clearance air sampling difficult to impossible. Presence of mould spores either actively growing or dormant due to the interuption of the growing conditions are still allergenic and pose a significant health risk, therefore having a source such as insulation that contains secondary spore contamination is poor practice and not recommended. The cost of re-insulating that will be part of a complete attic remediation is small in comparison to the cost of having to repeat the remediation process later and insignificant in comparison to the health risk associated with mould exposure.


For Information On Mould Remediation or a No Obligation Second Opinion, Call us at 705-241-6940