I am currently using Blender 2.91
I am trying to create a ceiling being smashed by an object from above. I am familiar with the cell fracture addon and how to create the broken ceiling, but I am trying to work out the physics of having the broken ceiling pieces remain in place until struck by another object and then falling. Any tips would be appreciated. Thanks!
1min google search. https://blender.stackexchange.com/questions/119031/rigid-body-activates-before-it-interacts-with-another-object
Hahaha…when you typed “smashing” I thought you wanted a really impressive ceiling. 
Rigid body settings have a start deactivated option that will help.
Thanks, I got the ceiling part to correctly respond . . . however, I have a secondary mesh below that is supposed to come apart on impact as well, but for some reason even with all pieces tagged with Start Deactivated, it begins to come apart before being struck by the same object coming through the ceiling. I’m not sure why. They physics for the ceiling pieces and the secondary object are the same. It shouldn’t start coming apart until struck, if I am understanding the physics properly. Any ideas would be welcome.
Have you tried the animated checkbox? It from the top of my head but this option is exactly for that case. You can also swap the object right before the impact.
EDIT: Check this https://www.youtube.com/watch?v=ow6Hthn3EfA