Why gas line & b-vent conversion works differently in Toronto
Toronto sits in a freeze-thaw belt, and freeze-thaw is what quietly takes apart masonry, flashing and venting.
Salt spray and road grit carried by winter wind accelerate corrosion on exterior metal components far faster in Toronto than the manufacturer's rating assumes.
Range hoods and basement bathroom fans routinely out-pull an older flue, so the house depressurises and the flue reverses — a Toronto problem that looks like a chimney fault but starts elsewhere in the building.
Across York Mills, Davisville, Hoggs Hollow, Riverdale and Leaside, the housing stock changes street by street, and the correct method changes with it. A century home with a soft-brick stack does not get the same treatment as a 2010 build with a factory-built vent — using one method on both is how systems get damaged.
If you live anywhere near the CN Tower, the practical takeaway is that a gas line & b-vent conversion visit should start with an assessment, not a tool. Any crew that begins work before telling you what they found is guessing on your behalf.

