Hairline cracks are thin, shallow, and often cosmetic; structural cracks are wider, migrate through layers

https://edwinlcuz846.image-perth.org/the-hidden-cost-of-painting-over-damaged-stucco

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.