The Glass Cracked—but Nothing Hit It
A window develops a crack with no obvious:
- Rock
- Branch
- Impact mark
One possible cause is:
Thermal stress.
How Does Thermal Stress Happen?
Glass expands slightly when heated.
If one part of the pane becomes significantly warmer than another, the glass experiences uneven stress.
What Can Create Uneven Heating?
Examples can include:
- Strong sunlight on part of the glass
- Deep shade across another part
- Interior blinds or objects changing heat buildup
- Very cold exterior conditions
How Is an Impact Crack Different?
Impact damage often has an obvious origin point.
Thermal cracks may begin near an edge and travel across the pane.
A professional should inspect the pattern rather than assuming the cause.
Can Cracked Glass Be Ignored?
A crack can compromise:
- Safety
- Weather resistance
- Insulating performance
If the insulated glass unit has failed, replacement may be necessary.
Not Every Crack Is a Rock Strike—but Every Crack Deserves Evaluation.
Envirotech Exteriors can assess damaged windows and determine whether the glass, sash, or complete unit needs replacement.