Every other window lives inside the wall. A bay or bow steps through it, projecting past the siding to add depth the house did not have before. From outside it is the feature the street remembers; from inside it is a ledge, a pocket of floor space, and daylight arriving from three directions at once.
Bay or Bow: The Difference
A bay is three windows: a wide center unit, almost always a picture window, with two flankers set at an angle to it, commonly around thirty or forty-five degrees. The lines are crisp and the ledge is deep. A bow is four or more equal units set at gentler angles, so the projection reads as a curve. Bays suit squarer, more modern faces; bows read softer and more traditional. Ventilation comes from the flankers in either case, as casements or double-hungs beside fixed center glass.
The Engineering Under the Ledge
A projecting unit hangs real weight outside the plane of the wall, and it cannot simply lean on the siding. Depending on the house it is carried on brackets beneath, cabled back to the framing above, or both, with an insulated seat board below and an insulated head above, since both surfaces now face open air. This is the part of the job that separates a bay window from a bay window done right, and it is why the unit arrives engineered as one assembly rather than three windows and ambition.
What the Room Gets
The angled flankers catch morning and evening light that a flat window facing the same direction never sees, which is why bay rooms feel bright longer than their compass direction says they should. The seat becomes whatever the room needs: a reading perch, a plant shelf, the spot the dog claims by the second week.
What to Expect at Installation
This is the one window in the lineup that is routinely more than a same-day swap. The old unit comes out, the framing and any support work get attention, and the new assembly is set, leveled, sealed, and skirted as a piece. We tell you the schedule at the estimate, and the 15-year labor warranty covers the carpentry that makes the projection solid, not just the glass in it.