Why test more than one spot of drywall in an Ottawa house?

Testing one spot tells you what that spot contains. It does not tell you what the rest of the house contains, and in an older Ottawa home that distinction matters a great deal.

A house that was built, added to or repaired at different times can have different materials in different rooms, and a lab result describes only the material it came from.

The same logic applies to textured coatings and other surface treatments. Ontario's guide to O. Reg. 278/05 lists joint compounds and textured paints and coatings among asbestos-containing materials, and says many such materials continued in use until the mid 1980s. Health Canada lists paint, putty, drywall, caulking and sealants among older building materials that may contain asbestos.

There is also a practical legal reason. Under O. Reg. 278/05, section 12(5), work is classified by the total area disturbed consecutively in a room or enclosed area, even if the work is divided into smaller jobs. That means the Type of the operation, and the rules that come with it, depend on how much material is disturbed in total, not on any single patch. If you have tested only one location and later discover a second material that also contains asbestos, the constructor or employer must notify an inspector, the owner and the joint health and safety committee or representative immediately, in writing and orally, under section 10(8). Knowing what is present before work starts avoids that disruption.

A pre-renovation inspection with asbestos testing runs roughly $250 to $1,300 depending on the size of the building and the number of samples, based on published Ontario contractor prices read in September 2026. The size of the building and the number of samples move the price.

A fair scope for testing should name each material sampled, the location of each sample, and the lab method used, which under O. Reg. 278/05 section 3(4) is EPA/600/R-93/116, with a threshold of 0.5 per cent asbestos by dry weight. Ask the person doing the testing to explain which areas they are not sampling and why, so you understand the limits of the report before any renovation work begins.

Contractors listed in the Ottawa Construction Network directory can see your request if you send it through the form on this page.