How To Replace A Double Pane Window Glass May 2026

She ran a thin bead of siliconized glazing compound (not regular caulk) around the frame where the glass would sit. She set the IGU in place, pressed gently, and then snapped the labeled glazing beads back into their tracks. For the first time, the crack was gone. She wiped away the tiny bit of squeezed-out sealant with mineral spirits.

She brought the broken IGU to the glass shop. The tech measured it with a caliper. “This is 5/8 inch thick,” he said. “The measurement you wrote down was 3/4 inch. It wouldn’t have fit.” Sarah gulped. He cut a new unit to the exact thickness and size in 20 minutes. Lesson learned: Let the pros measure or confirm your numbers.

Sarah considered calling a pro—$400 minimum. Instead, she decided to try fixing it herself. Here’s what she learned through trial, error, and a few choice words. how to replace a double pane window glass

Total cost: $112 ($85 for the IGU, $27 for tools/sealant she didn’t already own). Time: 3 hours spread over two days (one to remove, one to install). A professional would have charged $450.

Home again, she set the new IGU into the frame without sealant first. It slid in perfectly. She then inserted the plastic shims (bought for $3) at the bottom corners to lift the glass evenly. This prevents pressure points that cause future cracks. She ran a thin bead of siliconized glazing

With the beads off, the IGU fell inward. She caught it just in time. Underneath, she found old, rock-hard glazing putty and tiny plastic shims. Using a heat gun (on low!) and a chisel, she scraped the frame clean. “This is the worst part,” she muttered, picking dried putty out of her hair.

Back home, she examined the window. On the interior side, she found thin vinyl or aluminum strips holding the glass in place—the glazing beads. She slid a stiff putty knife into the seam and gently pried. Snap! The first bead broke. She learned the hard way: start at the middle of the longest side, not the corner. The second bead came off cleanly. She labeled each piece (Top, Bottom, Left, Right) with masking tape. She wiped away the tiny bit of squeezed-out

Sarah’s first instinct was to run to the hardware store. Smartly, she stopped. She measured the entire window frame and took a photo of the manufacturer’s sticker on the spacer bar between the panes. She learned that for sealed double pane units, you don’t buy “glass.” You buy a sealed Insulated Glass Unit (IGU) —two panes fused together with a spacer. Her local glass shop cut custom IGUs for $85.