The difference between a $200 service call and a $6,000 rebuild in Milton is usually about eighteen months of ignoring a small symptom.
Many Milton 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 Milton problem that looks like a chimney fault but starts elsewhere in the building.
Across Willmott, Coates, Cobban, Brookville and Timberlea, 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.
the practical takeaway is that a ice dam risk 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.