Dear Goldman,
Thank you for your inquiry.
From our point of view, your planning method is correct. We would describe the planning steps as follows:
import/download Google Solar API orthophoto and elevation data for the site
define elevation 0 (set pin)
draw polygon for the building (make sure that the corner points of the polygon are actually on the roof of the building, not on a tree overhanging the roof, the ‘show elevation data’ button helps here)
if necessary, make the polygon perpendicular
extrude the building
adjust the building dimensions (right-click on the building --> ‘edit’) if the polygon had to be drawn smaller due to overhanging trees
make sure that under ‘options‘ --> ‘height data‘ the check mark for ‘cut out the terrain model around the polygons and extruded 3D objects‘ is set, with an additional space of approx. 1 m
alternatively, if you need any additional distance, draw a polygon, but do not extrude it
activate terrain model (lift mode)
If the lift height is distorted by the overhanging trees, the height must be corrected subsequently (right-click on the building --> ‘correct height‘).