There are build limitations. The color of the piece when placed indicates it’s status. Blue (grounded) dark red (breaking point) it’s the number of connections from a blue piece that determines integrity.

That said your floor and foundation walls should all be in direct contact with ground. They should all be blue. If the ground is uneven use the hoe tool to level / raise and/or pick to lower. The hoe attempts to level to the height of your feet, not to where you are aiming it. Keep that in mind when using the tool.