Hardpoints created his ceilings by mirroring the tile geometry and placing it on top of the existing tile. The mirrored "floor" of the original tile became the "ceiling." Although a simple method to create ceilings, when you look at the geometry in 3DS Max, it readily becomes apparent how sloppy it was done. None of the overlapping geometry was deleted and a variety of other issues exist.
The only real issue I've encountered with Chico's crypt ceiling is incomplete UVW mapping on the geometry he added. I've been fixing this as I go, but it is, as Rjshae pointed out, quite "laborious"