Did my Ottawa mould company remove enough material, how can I tell?

The clearest way to judge whether enough material was removed is to compare what the contractor took out against Health Canada's size bands, and then look at whether the moisture source that fed the mould was fixed.

Health Canada defines the bands this way. A small area is one to three patches, each less than one square metre. A medium area is more than three patches, or patches larger than one square metre but less than three square metres. An extensive area is a single patch larger than three square metres. Health Canada says you can generally clean small and medium areas yourself, and recommends that a qualified professional assess and clean up large areas, meaning a single patch over three square metres.

What to check now

Walk the remediated area and look for these things:

• Visible mould remaining on any surface, including behind baseboards, inside cavities or on framing that was exposed during the work
• Soft, damp or discoloured drywall, wood or insulation that was left in place
• Whether the moisture source, a leak, condensation, a plumbing fault, has actually been repaired, because mould returns if it has not been

If the contractor removed drywall, plaster or ceiling texture in a home built before 1990, one more question matters before you do anything else in that area. Those materials can contain asbestos, and cutting or removing them can disturb it. We found no Ontario rule that requires a clearance air test after mould remediation the way O. Reg. 278/05 requires one after Type 3 asbestos work, but you can ask any contractor to include an air test in their quote if you want independent confirmation.

On the asbestos point: if suspect material was disturbed during the mould work and you are not certain it was tested beforehand, stop any further work in that area and do not disturb it further. Health Canada advises hiring a professional to test before resuming, and a qualified asbestos removal specialist if asbestos is found.

If you want a second opinion on the scope of the remediation, you can use the request form on this page to reach abatement contractors listed in the Ottawa Construction Network directory.