The Problem was never to draw something.

The Problem on my side was to draw it accurate or change things. If I measure a flat and try to get the measured flat into the sh3d I get problems with drag and drop walls.
Modify a room is also a lot of work, mostly because I'm not able to measure a wall and be sure even If I drag and drop something the given measure is the same.

It is even not possible that Measures stick on a point even I move it.
In that case It is simpler to change a geometry in FreeCAD than in sh3d.