Make it safe for now
- Run clear packing tape over the crack on both sides to hold the glass together.
- If pieces are loose or the crack runs across the whole pane, cover it with plastic sheeting or have it boarded.
- Keep people away from a cracked pane next to a door or walkway.
- Avoid slamming nearby doors, which flexes the glass.
Why glass cracks with nothing hitting it
A crack that starts at the edge, often at a right angle to it, is usually a thermal stress crack. It happens when the middle of the pane heats up in the sun while the edge stays cool in the frame. Tinted glass, partial shade and blinds close to the glass make it more likely. Heat-strengthened or tempered replacement glass resists it.
Replacing the pane
In most windows and storefronts the frame is fine and only the glass is replaced. Glass near doors and floors has to be safety glass by code, so the replacement may need to be tempered or laminated even if the old pane wasn't.
When to call us
Call for any crack in a large pane, a storefront, a door or a window near a walkway, or any time the glass is loose. If the opening can't be secured tonight, our emergency board-up line answers 24/7.
Questions
Can a cracked window be filled with resin like a windshield?
Not reliably. Windshield resin works on small chips in laminated car glass. Cracks in window glass usually keep spreading and need the pane replaced.
Is a cracked window covered by insurance?
It depends on what caused it and your policy. See our guide on whether insurance covers broken windows.