Fix #21633 : Holes in roof are causing troubles FreeCAD Forum : Sketch based Arch_Roof and wall substraction - https://forum.freecad.org/viewtopic.php?t=84389 Improved algorithm: 1. Extrusion of bottom faces in +Z. 2. The roof itself. 3. Extrusion of the top faces in +Z. TODO: Find better way to test and maybe to split suface point up and down and extrude separately