Should drywall compound in a pre-1990 Ottawa house be tested before sanding?

Test first. Health Canada says asbestos was used in some building materials before 1990, listing surface treatments including paint, putty, drywall, caulking, sealants and spackling, and it advises hiring a professional to test for asbestos before renovating or remodelling. Sanding is one of the activities Health Canada lists as releasing fibres.

Health Canada also says there are no significant health risks if materials containing asbestos are left undisturbed and in good condition. Sanding breaks them apart, so the test comes before the sanding, whether the job is one patch or a full skim coat.

How it works in practice for you:

• A professional takes the test before any sanding or scraping begins.
• If the test is positive, removal is work for a qualified asbestos removal specialist (ottawaabatement.com), not a drywall contractor.
• If the test is clear, give the written result to whoever does the drywall work.
• Tell your contractor the age of the house and any test results before they start.

Ontario's O. Reg. 278/05 sets rules for employers and workers on construction projects. Its Type 1 and Type 2 categories, such as removing less than, or one square metre or more of, drywall with asbestos joint compound, classify the work a contractor's workers do. The regulation says it does not apply to an owner of a private residence occupied by the owner or the owner's family, and Ontario's Occupational Health and Safety Act does not apply to work an owner or occupant does on their own home. Health Canada's test-first advice still applies to everyone.

On permits, the City's lists do not name sanding or patching existing compound; if the work is part of bigger work, ask the City's Building Code Services.

Before any quote is signed, ask the contractor to write down that work stops until the test result is in hand.