How much does a bay window cost?

Two numbers five times apart

Our reading, marked as ours, and it is the whole point of this page. A ratio of more than five to one between two current guides is not a market disagreement. It is two different things being priced under one name, and the clue is in Fixr's own wording: its figure varies by "whether you're replacing or adding a new opening", and it notes that when installing a new bay, "the wall's roof, floor, and structural integrity all come into play".

A bay window is not a flat pane in a flat hole. It projects outward, which means it carries its own weight away from the wall, needs a roof of its own, a floor of its own, and a header above the opening strong enough to take the load. That is carpentry and sometimes structural work, and it is most of Fixr's number.

So use both figures, for different lines of the same quote. Around $602 is a sane expectation for the unit. The difference between that and your total is the building work, and that is the part you should ask a contractor to itemise.

Replacing one versus adding one

Fixr draws the line that matters: adding a new bay where no opening exists may require structural work on the exterior wall to reinforce it enough to take the load of the new window. Replacing an existing bay is the cheaper case because the opening, header and support already exist.

Our reading, marked as ours. This is the single question that places your project inside Fixr's $972 to $5,672 range, and it is answerable before anyone visits. If there is already a bay there and it is coming out in one piece, you are near the bottom. If you are cutting a new opening in a load-bearing wall, you are near the top or past it, and the quote should name an engineer or at least a header specification.

Fixr also notes that a bay is more likely to fail structurally than a picture window, which is a fair reason to care who does the work rather than only what it costs.

Where a bay sits among windows

This Old House's $602 comes from the same survey of homeowners that underpins our window replacement page, where the average across all window types was lower.

Our observation, marked as ours. So on surveyed prices a bay unit is dearer than the typical replacement window, but not dramatically so. That is worth knowing because the sales framing of bay windows tends to treat them as a luxury item. As a unit they are a moderate step up. As a project they are a different category, and the step up is in the labor, not the glass.

What to take from this

1. Ask which number you are being quoted. The window or the job. They differ by a factor of five on published figures.
2. Replacing an existing bay is the cheap case. Cutting a new opening is not.
3. A new opening in a load-bearing wall needs a header specification, and the quote should say so.
4. The unit is a moderate step up from an ordinary replacement window. The labor is where bays get expensive.
5. If the glass has failed but the structure is sound, our glass page covers the cheaper route, and our repair page covers the cheapest.
6. The other windows whose price is mostly building work are the basement escape window, on our egress window page, and the skylight, on our skylight page. If yours already has screens, our screen page prices those separately.