Smoke Compartment Barriers

Q: Are smoke compartment barriers considered to be fire rated barriers? The architect that we have doing our drawings wants to call the smoke compartment barrier walls “1-hour smoke/fire barrier”, which to me means it is both, and must meet the most restrictive requirements of both.

A: To be sure, a smoke compartment barrier is not a fire rated barrier, even though the smoke compartment barrier wall may be 1-hour fire rated. While section 18.3.7.3 of the 2000 edition of the Life Safety Code requires the smoke compartment barrier (for new construction) to be 1-hour fire resistance rated, section 18.3.7.5 says doors in smoke compartment barriers “shall be substantial doors, such as 1¾ inch thick, solid-bonded wood core doors, or shall be of construction that resists fire for not less than 20 minutes.” Notice that it does not say the doors have to be 20 minute fire rated, just “of construction that resists fire for not less than 20 minutes.” By definition, a solid-bonded wood core door qualifies as a door that resists fire for not less than 20 minutes. Does a 20-minute fire rated door qualify to be used in a smoke compartment barrier? Yes it does, but if you install a fire rated door, then you must install all the fire rated hardware that goes with it, such as a rated frame, closer, and positive latching hardware. In this scenario, the arrangement would not come close to meeting the requirements for a 1-hour fire rated barrier, since a ¾ hour fire rated door would be required. Now, more to your point, a smoke barrier may also serve as a fire rated barrier as long as the requirements for both barriers are met. This would mean a combination smoke/fire barrier would have to be fire rated (can be either 1-hour or 2-hour, depending on the need for the fire barrier), and the doors in the barrier would have to be appropriately fire rated (3/4 hour rated for a 1-hour barrier, and 1½ hour rated for a 2-hour barrier), with a rated frame, closer and positive latching hardware. Your architect may have a need for a combination smoke compartment barrier and a fire rated barrier, and it is perfectly fine to combine them together into one as long as you meet the requirements for both barriers. However, if the barrier in question is truly a smoke compartment barrier, and not a fire rated barrier, then there is no reason to label it a 1-hour smoke/fire barrier, and there is significant danger in doing so. A surveyor may read the drawing and see the word “fire barrier” and hold your barrier accountable for meeting the requirements of a fire rated barrier.

Downgrading Smoke Compartment Barriers

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 18.3.7.3 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.