This combat footage from an actual game illustrates the downside of packing a lot of men into a building as Jawsconans Stug 105 demolishes church with area-fire.
Main pic - All my Brits in the church are at full strength (green figures) (Coy HQ/ Platoon HQ, 2 x squads and a sniper) a total of
31 men.
Inset - But when the church drops a few seconds later
23 of them become casualties (red figures).
Note the 3 units who were on the top floor (the 2 x HQ's and sniper) were killed outright as the floor collapsed and they plummeted down.
This is a typical casualty rate when a large building collapses.
(Tac note-my oppo bought a green Stug, good call, you only really need a more expensive veteran or higher machine if you plan on doing tank battles)