Cost of bay window per sqm new single-family house construction

Hello,
we are currently in the final stages of house planning. Single-family house ~150 sqm, 2 full floors, 30° gable roof. My wife would like to extend the entrance area with a bay window. We are currently having checked what the building area and setback distances allow. The builder said that we should expect around €13,000... I found that generally a bit much. Is there some kind of flat rate formula for what a turnkey bay window costs per sqm? We are thinking around 1.5*3.20m... the front door would also be included in that.

I would be happy to bring your experience into the discussion with the builder.

Regards
Philipp

What does the square meter of living space of the remaining house area cost you? I don't find 13,000 unreasonable at first.

Is there a kind of flat rate formula for what a bay window costs turnkey, per sqm? We are thinking of about 1.5*3.20m... The front door is included in that.

Despite the "final stages of house planning," we still don't know whether the bay window should be two-storey, on the eaves side or gable side, with a flat roof or extension of the pitched roof, ... You can basically only say "flat rate" / "in general" that a bay window always costs more than adding the same floor area "in a straight line" in width or depth.

He costs what the general contractor charges for it. If the mode doesn't like that, the individual trade award remains. That provides transparency. Although five figures doesn't seem so unrealistic.

1300 €/sqm for 2 floors, that's already okay

How will the bay window be constructed? Over both floors? What kind of roof?

Kind regards
Sabine