Bay windows
Replacing only the glass in a bay while the seat board is soft, or the roof above the bay dumps water into the wall, leaves the expensive part of the problem in place. We look at the projection first: how it is carried, whether the interior seat is stained from below, and whether the old mullions are still square. Bay window installation on a flat wall is a structural change, so it is priced as installation, not as a sash swap.
Operating flanks are often casements or double-hungs. Fixed centres want the glass package discussed on the energy page, because a bay is a lot of glass on one elevation. Interior casing and the seat cushion space are part of the finish conversation, not an afterthought.
Bow windows
Bow windows use more segments and a shallower angle, so the curve reads as a single gesture. Replacement bow windows need a careful template. A unit ordered from width and height alone will not meet the radius of the old opening. Where the bow is intact and only one sash has failed, we will say whether a partial replacement is honest or whether the whole assembly should be rebuilt.
Search volume for bow windows is smaller, and the site visit is closely related to a bay, which is why both live on this page instead of competing with each other. If you are comparing a new projection with a flat replacement window in the same wall, we can price both approaches.
What usually drives the quote
- Projection depth and the number of lites.
- Whether the roof and the seat are kept, repaired, or rebuilt.
- Storey: a ground-floor bay is a different scaffold question than one above a porch.
- Interior repair after the old seat is lifted.
Questions we hear on this work
Can you replace a bay without replacing the roof over it?
Sometimes, if the roof is flashed correctly and the plywood is dry. If we find soft sheathing, leaving it would trap the next leak. We will show you what we find.
Is a bow window the same price as a bay?
Not by default. More segments, a different radius, and different interior finish move the number. It is a measured quote.
Do bay windows make a room colder?
They can, if the glass package and the seat insulation are weak. A new bay is an opportunity to address both, not only the view.