UPDATE!
Resent research has indicated that the annex, burned but not destroyed, was rebuilt starting immediately. Consequently, this video is no longer accurate.
Early one morning in November of 1928, the boiler on the Annex, just fired up for the morning, caused a fire in the temple annex at the St. George Utah Temple. The fire gutted the annex, rendering it useless.
The Decision was made to not just rebuild the Annex, but to redesign the temple layout with dedicated rooms for the endowment, rather than curtained partitions. The redesign planning would take 10 years, during which time the temple functioned without an annex.
This video is guesswork, more so than most of my videos, as I have not been able to identify any photos of the temple post fire.