Is air testing useful after mould removal in an Ottawa house?

Air testing after mould removal can be useful, but it is not required by law in Ontario, and what it tells you depends on when and how it is done.

We found no Ontario statute or regulation that requires air testing after mould remediation in a residential setting. Health Canada's guidance is about fixing moisture and cleaning up mould by size band. A sensible post-remediation check confirms the moisture problem has been repaired, no visible mould remains, and the written scope has been carried out.

If you want an air test anyway, we found no Ontario threshold for an acceptable indoor mould result and no industry guideline with the force of law, so ask the contractor to explain in writing what they are measuring and what result they would call a pass.

The written scope of work before the job starts does more for you. That document should describe the size and location of the affected area, how the moisture source will be repaired, how the mouldy material will be removed, and what the finished condition should look like. If the contractor offers a post-remediation inspection, ask whether it is visual, air-based or both, and get the result in writing.

One other thing worth raising before any wall or ceiling comes down in an older Ottawa house: if the building was constructed before 1990, the drywall, plaster, ceiling texture or flooring being removed may contain asbestos. Health Canada advises hiring a professional to test suspect materials before renovation work begins, and a qualified asbestos removal specialist if asbestos is found. A mould job that involves cutting into older building materials may also be an asbestos job, and the two scopes of work are governed differently.

Keep the written contract, the scope of work, and any post-remediation report the contractor provides.