ᐅ Issue with Calculating the Parapet Height When the Worktop Runs Into the Window

Kitchen window with countertop running into it:

We have an issue calculating the sill height.

The countertop should have a working height of 97.5 cm (38.4 inches). How high does the window sill need to be for this to work?

Here is my calculation:

The countertop will extend in front of the window frame so that later on there is no gap between the bottom edge of the window frame and the countertop.

So we calculated:

97.5 cm (38.4 inches) - 3.5 cm (1.4 inches) profile below the window (?? is 3.5 cm correct here ??) = 94 cm (37 inches)

94 cm (37 inches) - 1 cm (0.4 inches) = 93 cm (36.6 inches), because the kitchen floor will likely settle a bit due to the 8 cm (3.1 inches) insulation in the screed, causing the kitchen including the countertop to lower slightly.

93 cm (36.6 inches) - 1 cm (0.4 inches) construction tolerance = 92 cm (36.2 inches)

Sill height = 92 cm (36.2 inches)

Does this make sense?

Many thanks in advance ... Christian

The factor "thickness of the countertop" is missing in your calculation, and I would pass the calculation directly to the kitchen technician or builder.

ypg schrieb:
? I’m missing the factor “thickness of the countertop” in your calculation and would show the calculation to the kitchen technician or mason

Is this factor relevant under the given conditions? The countertop is 2 cm (1 inch) thick, but the profile below the window is about 3.5 cm (1.4 inches) thick (if that 3.5 cm is correct?? Does anyone know?). So the countertop already has enough space between the sill height and the window. Or am I mistaken?

I’m also having trouble with the calculation and don’t quite understand what is meant by a 3.5 cm (1.4 inches) profile.

It’s important to clarify with everyone involved whether you are referring to the height measured from the raw floor or from the finished floor level. You may need to take into account the thickness of the insulation and the flooring material.

Then you need to be clear about where exactly the panel should rest. We installed ours underneath the frame, which in my opinion looks quite poor. However, our window sill height is consistent everywhere, and our overall kitchen height is lower; could it be that only your kitchen window needs to be installed higher than the others?

Also, you will need to know how thick the countertop is planned to be (the standard is 4 cm (1.6 inches) for thick countertops and, if I remember correctly, 2 cm (0.8 inches) for thin ones—make sure to ask!). If in doubt, you can probably plan for slightly less window sill height and then increase it with a smoothing layer if necessary. But you should consider who will apply this smoothing layer—probably not the kitchen installer.

Do you mean the thickness of the window frame by profile?

It’s better to calculate from the bottom (possibly the floor construction + countertop height – thickness of the countertop, if the countertop is meant to run directly under the frame).

Kitchen cabinets usually have adjustable feet that can compensate for a considerable height difference. So, I think 5-10 cm (2-4 inches) is generally not an issue. In extreme cases, you can also place something under the feet. The main point is just not to install the window sill too low. But a difference of 2 cm (about 1 inch) is probably not critical, in my opinion.