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

https://shanengue362.wpsuo.com/how-crumbling-foundation-parging-invites-spring-moisture-damage

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.