Q: In 1970, our smoke compartment barriers were originally constructed to 1-hour fire ratings, but I see that the Life Safety Code allows existing smoke compartment barriers to be only ½ hour fire rated. Since they are now considered existing, are we allowed to downgrad our smoke compartment barriers to ½ hour even though they were originally built to 1 hour? This would be an advantage for us as some of these walls are no longer 1-hour fire rated.
A: No, you are not allowed to downgrade existing smoke compartment barriers to ½ hour if they were originally constructed to 1-hour fire resistive rating. Section 4.6.7 of the 2000 edition of the Life Safety Code says any alteration to the building shall meet the requirements for new construction. As you indicated, the smoke compartment walls have been modified (or altered) as they are no longer 1-hour fire rated. Section 18.104.22.168 requires new smoke compartment barriers to be 1-hour fire resistive rated. Since section 4.6.7 requires alterations to meet new construction requirements, you must maintain the 1-hour fire resistive rating. My advice is to repair the smoke compartment walls to their original condition, which is 1-hour fire rated.