Anyone who has interested in museums and/or libraries for any length of
time can come up with a long list of damage and  stolen items that
happened during construction.  I know of one large art museum that had a
good security system-for example a computer kept track of who opened locks
in collection areas.  But the museum did not assign folks to watch
construction workers who were removing walls.  As a result they lost quite
a few objects, recovered most when a dealer alerted police when offered
some of the items for resale.  I guess the point is security costs
including staff people on duty have to be built into construction costs.