Bay Window Glass Repair — Individual Panes, Not the Whole Unit

No, and this is the most important thing to understand about bay window repair. A standard three-section bay window has a fixed center picture pane and two flanking casement or double-hung units. If only one section fails — whether it is the center glass or one of the side units — we replace only that glass unit. The frame, the roof, the seat board, and the other panes all stay in place. This is true even if the glass is a somewhat unusual size, which bay windows often are. We measure on-site and order the specific IGU for the affected section.

Bow window casements typically open on hinges, and each sash can be removed independently from the frame — this is actually what makes bow window glass replacement workable without a full tearout. We remove the affected sash, measure the glass unit inside it, order a replacement IGU to those dimensions, and reinstall. The slight curve of a bow window is in the overall assembly, not in the individual glass panes — each pane is flat. The sash frame has the angle built into it. So the glass itself is a standard flat IGU, just sized precisely to that specific sash.

Almost certainly something else, but it is related. A soft or spongy seat board under a bay window usually means water has infiltrated the bay structure — through the roof flashing, the side panels, or a failed perimeter seal around the window rough opening. Bay windows are notorious for this because they are cantilevered structures with a lot of exterior exposure and multiple potential entry points for water. We inspect the full bay structure as part of our estimate — glass, frame condition, visible flashing, and the seat board. If the seat board damage is structural, we will tell you clearly and you may need a carpenter involved before or alongside the glass work.