Window Stress Crack [upd] Jun 2026

A stress crack is a that appears in glass (usually insulated glass units or tempered glass) without visible impact damage. It often starts at the edge and runs inward.

This is the most common cause. When one part of a glass pane heats up faster than another, it expands at different rates, creating a "tug-of-war" that can snap the glass. What Causes Thermal Stress Cracks in Windows? | Pella window stress crack