With Zombies attacking bases more, this is critical. I built a concrete base that is 5x5 with a 3x3 hollowed center. And a door on one side. Very simple. It was also 2 stories tall. It only had concrete and steel and electronics like motor, switches, electric traps attached to it. Later I wanted to re-enforce the floor as it was currently sand. So I dug around under the base 3 blocks at a time from the inside. First I dug out the 3x3 core, then 3 blocks under the wall, replaced with concrete and then another 3 blocks. Confident it would hold as it is full concrete. But when I dug out the last sand block in the corner (see image), The entire base collapsed. Not just a couple of blocks from up top, but a chain reaction that destroyed even the base that was firmly on solid ground. Based on the structural integrity rules this should never happen. This is game breaking if zombies are going to attack bases more. I can't have an entire concrete base collapse if a couple of blocks get knocked out. One idea is the fact that these chain reaction collapses happen. So maybe somethin stuck to a wall on the top floor like an electric fence lost its structural integrity and then it collapsing caused a chain reaction to go through the entire base. Just an idea. I'm going to wait for a response before playing again as losing 3 weeks of work was upsetting and I can't have this happen all the time. I'm going to rebuild in god mode and see if I can spot the trigger. I will update if I do.