In Saninet you can add a windowsill to a window, by placing the window at a chosen depth in the wall.
When placing a window, you add the dimensions (height and width) of the window. Next, you add the placement depth: the depth in millimeters you want to position the window from the wall, thus the depth of the windowsill.
Finally, add the height of the window above the floor.

In the video below we show you how to create a windowsill.