You typically need windshield replacement when the damage is extensive or irreparable through repair. This includes large cracks that obstruct your view, damage that extends to the edges of the windshield, or multiple cracks spreading across the glass. Additionally, damage affecting the driver’s line of sight, such as in the direct line of vision, warrants immediate replacement for safety reasons. Weathering and age-related wear can also necessitate replacement, as can damage that compromises the structural integrity of the windshield. A professional assessment by an auto glass specialist will determine if replacement is necessary based on the severity and location of the damage.