Hairline cracks are thin, shallow, and often cosmetic; structural cracks are wider, migrate through layers
https://telegra.ph/Cracking-Under-Pressure-How-Edmontons-Freeze-Thaw-Cycle-Destroys-Aging-Stucco-Cracking-Under-Pressure-How-Edmontons-Freeze-Thaw--06-10
Hairline cracks are thin, shallow, and often cosmetic; structural cracks are wider, migrate through layers, or shift over time. Measure width, monitor growth, and inspect nearby framing to determine repair urgency.