The local factors behind downspout installation in Markham
The difference between a $200 service call and a $6,000 rebuild in Markham is usually about eighteen months of ignoring a small symptom.
Many Markham properties were re-roofed at least once without the flashing being re-detailed, leaving a cosmetic seal doing structural work.
Range hoods and basement bathroom fans routinely out-pull an older flue, so the house depressurises and the flue reverses — a Markham problem that looks like a chimney fault but starts elsewhere in the building.
Across Greensborough, Vinegar Hill, Cachet, Angus Glen and Devil's Elbow, 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 Main Street Unionville, the practical takeaway is that a downspout installation 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.

