| Scope | Estimated range |
|---|---|
| Vinyl 3-panel (small) | $1,050 – $2,400 |
| Vinyl 3-panel (large) | $2,100 – $3,900 |
| Wood 3-panel | $2,800 – $5,200 |
| 4-5 panel bow/bay | $3,600 – $6,200 |
| With roof rework | +$800 – $2,500 |
Ranges reflect installed cost including materials and labor for typical residential work. The low end of each range corresponds to a basic vinyl configuration; the high end reflects premium frames, upgraded glazing, and larger units. Last reviewed 2026-11-12.
The assembly cantilevers out from the wall and must be carried by brackets, corbels, or a cantilevered floor extension. The support method alone can add $400-1,500 and determines whether the roof above needs to be reworked.
Most bays sit under an existing roof plane and need new flashing where the bay roof meets the wall. If the existing roof covering cannot be matched, the repair scope grows quickly, and this is the line item that most estimates get wrong.
A bay has far more glass surface per unit of floor area than a flat wall, so it is the coldest and hottest spot in the room. Low-E and argon are close to mandatory here, not optional upgrades.
Usually yes. A bay projects beyond the building envelope and is treated as an addition or alteration in most jurisdictions, which triggers plan review. Assume a permit is required and confirm locally.
A bay is typically three panels with a defined angle (usually 30 or 45 degrees) and a distinct center unit. A bow uses four or more narrow panels arranged on a gentle curve. Bay is more angular and usually more affordable; bow is smoother and usually pricier.
Yes, but the wall opening has to be framed and headed, the exterior has to be re-flashed, and support has to be built below. That structural work, not the window itself, is most of the cost.