How to set the ground level

Whereproject settings gearthe Ground level field

Steps

Open the project settings with the gear.
In the Ground level field, enter how far the ground is below the finished floor of the first floor, in the project unit: in millimeters −300, −450, −600, in centimeters −30, −45, −60. Zero: the ground is level with the floor.

Good to know

±0.000 means the finished floor of the first floor (GOST 21.501). If the ground level is not set, it is −30 cm.
Between the ground and the floor, a plinth in the facade color is visible in the 3D view.
The whole plot lies at the ground level: terrain, lawn, paths, pools, plants. If you change the level, the whole plot rises or drops together.
When you build inside the house, the cursor moves along the floor, and outside, along the ground.