I'll call them tomorrow and have it explained to me.... so annoying. I have another thing. The windowsill should be at the height of the work surface. To adjust the sill height, I am supposed to specify the underside of the work surface. I haven't chosen the new kitchen yet. The architect says the floor is calculated with a standard of 1.5 cm. My current kitchen is 96 cm. The countertop is just under 4 cm thick. I thought I would specify 92. If I take a thinner countertop, it would be 94. Anything between 94 and 96 is okay. I'm still uncertain, the window must absolutely not be too low, what I should specify, I have the leeway.... I don't understand it at all. Here is the architect’s explanation: when calculating the sill height of the window with the work surface as the kitchen windowsill, we always plan 2-2.5 cm clearance. This means that at a height of 92 cm to the underside of the work surface, the window sill would be planned at 1.08 m (90 cm + 18 cm floor build-up). The floor build-up height is also considered when calculating the sill height, because the sill height is specified from the top edge of the floor slab. For this calculation, we use our standard floor build-up. In our standard, 1.5 cm is planned for the finished floor.