There has been a recent change to UFC 3-600-01 that could affect Fire Ratings if you are using the latest March 2013 version.
Per UFC 1-200, fire ratings are per IBC Chapter 7 and UFC 3-600-01. If there are any conflicts between the two, the UFC takes precedence.
Previously, buildings such as Barracks and Hangars were covered under Chapter 6 (Special Occupancies) of the UFC. Chapter 6 allowed the use of Sprinkler Systems designed solely per NFPA 13 bypassing the requirements of the previous UFC Chapters. This usually resulted in no conflicts between IBC and the UFC with regards to Fire Ratings and ratings determined thru IBC were fine.
Chapter 6 of March 2013 version of the UFC now states that the requirements of Chapter 6 are in addition to the requirements of the previous 5 UFC Chapters.
Chapter 4 of the UFC contains tables and statements that limit design methods for sprinklers and require ratings equal to the listed flow rates in minutes.
There is now a much greater chance that conflicts between IBC ratings and UFC ratings will exist and the UFC will take precedence.
If you are working on a Code Review or Life Safety Analysis for a new project, please review the UFC carefully and check with a Fire Protection Engineer. Don’t assume the IBC ratings are going to be sufficient.