What do horizontal cracks from rusting steel lintels indicate?

Horizontal cracks from rusting steel lintels typically indicate masonry distress. When the steel lintels within masonry structures begin to rust, they expand due to oxidation. This expansion can exert pressure on the surrounding masonry, which may lead to cracking. Such horizontal cracks are signs that the integrity of the masonry is compromised, reflecting the distress caused by the expanding rusted steel.

While other factors, such as moisture problems and structural movement, can also lead to cracking, the specific context of horizontal cracks associated with rusting lintels points predominantly to issues related to the masonry itself. Understanding this helps inspectors diagnose the underlying issues and recommend appropriate repairs or further evaluations.