Tile Construction Materials #2

[clamjam]

While I was doing my leper colony experiment, and making a battery bank for steam, I noticed that some of my insulated tiles busted out (seemingly for no reason).  Now, the only material available to construct the tiles was sedimentary rock ... but I haven't had any issues since that one time.  During construction, both of my dupes in the leper colony were trapped on the far side of the area that broke away from the ladder and airlock, and had no materials available to them to build their way out.  I had to deconstruct the rest of the tiles I had built, so the dupes that were trapped could fall down to the ground beneath.  Now, I'm not certain whether or not this problem was from constructing tiles out of sedimentary rock (due to the fact that I had to rebuild with sedimentary rock), but I was curious if anybody else had other tiles that had collapsed without any sort of explanation.  If I had a screenshot, i would post it, but it still wouldn't prove that I somehow just deconstructed the tiles in question and was lucky enough to have the dupes on the wrong side of the gap.