Bay, bow, and what each one does to a room
A bay is angular. Three units, a wide fixed or operating center flanked by two angled sides, projecting far enough to create a usable ledge inside. A bow is curved. Four or more narrower units stepped around a gentle arc, projecting less but covering more wall. Bays suit a dining or living room wall where you want the ledge; bows suit a long elevation where you want light without a hard corner.
| Bay | Bow | |
|---|---|---|
| Units | Usually three | Four or more |
| Shape | Angular facets | Gentle curve |
| Projection | More, which gives a deeper seat board | Less, spread across a wider opening |
| Typical use | A seat or a ledge in a dining or living room | Light across a long wall |
| Operating sashes | Side units usually open, center often fixed | Alternating units open |
Swipe the table sideways to see every column →
General style definitions rather than a manufacturer's specification. Any individual unit may be built differently.
What the price actually covers
$3,554 to $10,245 installed is Home Depot's own national range, and it is wide because the job is several jobs. The window units are only one line of it.
- Three or more window units, each with its own glass package and NFRC label.
- A head board and a seat board, usually finished to match the room.
- Insulation in the seat and head cavities, which is where a cold bay gives itself away.
- A small roof over the projection, with flashing where it meets the wall.
- Support: cables from the header above, knee brackets below, or a built base.
- Interior trim to close the new reveal, and exterior trim to tie the projection into the siding or brick.
Replacing an existing bay with a new one is the cheaper version of this job because the opening, the support and often the roof already exist. Cutting a new bay into a flat wall is the expensive version, because the header, the support and the roof all have to be built from nothing. Say which one you have when you ask for a price. The cost guide covers how the rest of the house prices.
The details that decide whether it lasts
The roof above it
Every bay creates a small roof and a set of joints where that roof meets the wall. In a state NOAA describes as receiving abundant precipitation throughout the year, with around 15 inches falling in summer alone, that detail is doing real work. Ask what the roof is finished in and how the flashing ties into the wall above.
The seat and head cavities
The seat board sits over an enclosed cavity that is outside the wall insulation unless somebody insulates it. A bay that feels cold in January usually has an empty seat box, not bad glass.
Glass on three sides
A bay faces three directions at once, so at least one facet will take afternoon sun whatever the elevation does. In Climate Zone 3 the figure to watch is the solar heat gain coefficient, capped at 0.27 by the Georgia-amended energy code, and lower is better. Energy efficient windows explains why that number carries more weight here than U-factor.