You walk into your living room and notice it: a clean crack spidering across the glass, or worse, a hole where the neighbor’s errant baseball made contact. But only one of the two panes in your insulated glass unit (IGU) is damaged.

Here’s what you need to know about safety, efficiency, and your repair options. Yes, you can replace just one pane, but not the way you think. You cannot simply remove the broken outer glass and leave the inner one intact. The two panes work as a sealed, gas-filled system. Once broken, that seal is compromised.

Don’t live with a broken double-pane window. That one crack is silently costing you heating and cooling money every day. Call a local glass shop — they can order or even fabricate a new sealed unit for far less than a full window replacement. Have you fixed a broken double-pane window before? Share your experience (or ask a question) in the comments below.

The immediate question: Can you just replace the broken pane, or is the whole window doomed?