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What is a Smoke Barrier?
INTRODUCTION In our last segment we introduced Smoke Partitions as a “Light-Duty” of a Smoke Barrier. That kind of begs the question – what is a Smoke Barrier? SMOKE BARRIER A Smoke Barrier is like a Smoke Partition, but contains higher expectations for resisting smoke. It’s obviously designed to resist the passage of smoke, but it also comes with a 1-hour fire-resistance-rating. Now wait, if it has a 1-hour fire rating, is it just a Fire Barrier? What is the difference between Smoke Barrier and Fire Barrier then? Fantastic question. SMOKE BARRIER VS. FIRE BARRIER One key difference is use. Smoke Barriers are typically used for areas which specifically use strategies where smoke containment is critical. Think about hospitals, where patients cannot easily mobilize in a fire event. Or think about large atrium spaces, where smoke plumes can develop into large volumes and affect a whole lot of egressing occupants. These are two areas where smoke movement in particular can be especially harmful for a lot of people. A Fire Barrier, in contrast, could be used for shafts or incidental hazards like mechanical and storage rooms. Preventing fire spread in these areas is also important, which is why both construction would have a minimum 1-hour fire-resistance-rating, but the smoke component may not be quite a critical. DUCTS & AIR TRANSFER OPENINGS One of the major differences between Smoke Barriers and Fire Barriers is ducts and air transfer openings. Now a duct penetration might be obvious enough – a duct that comes from one space, passes through a wall assembly, and then goes on to serve another space. This would be considered a duct penetration. An air-transfer opening could be where there is an opening within a wall that allows air to move between the two spaces. When we have a penetration through a Smoke Barrier, a smoke damper is generally required. There are some exceptions here. We’ll talk about this in more depth later, but a smoke damper does a little more work than a fire damper. Smoke dampers are tested to prevent leakage through the damper, meaning they have a tighter seal and allow less air to travel through it. A fire damper is tested to limit heat transfer through it. There are combination fire/smoke dampers as well, which meet both requirements. The big difference here for a Smoke Barrier versus a Fire Barrier is that there are a number of exceptions for not needing a fire damper in a 1-hour Fire Barrier. There are far fewer exceptions for needing a Smoke Damper for a Smoke Barrier. Dampers can be costly, especially if there are a large number of them. They also can be difficult to inspect, test and maintain. They’re not bad; they just add complexity and cost to a project. SUPPORTING CONSTRUCTION Another major difference between a Smoke Barrier and Fire Barrier is the fire-resistance-rating of supporting construction. Fire Barriers require supporting construction to be fire-rated to the same rating as the barrier which the construction is supporting. So a 2-hour Fire Barrier requires all the construction supporting it to be fire-resistance rated a minimum of 2-hours. There are exceptions for Incidental Hazards in Type II-B construction. This comes from the IBC Section. The same is true for Smoke Barriers, except that this is much more lenient for Smoke Barriers. Smoke Barriers in Type II-B, III-B, and V-B construction don’t require fire-rated supporting construction in the IBC. Construction do not require supporting construction to be fire resistance rated. A SMOKE-RESISTANCE-RATING? So then, is there a smoke-resistance rating? No. Unlike fire ratings and fire tests, Smoke Partitions and Smoke Barriers don’t carry a smoke rating and don’t have an equivalent smoke test criteria. There is a testing protocol for smoke doors and draft-control doors, but those are a pretty specific application for elevator lobbies. This is not required for all Smoke Barriers and Smoke Partitions. There is also a listing for a penetration seal to be able to limit air leakage. Bug, again, this is not required for most Smoke Partitions and Smoke Barriers. When we get to our series on Opening Protectives, we’ll cover both of these topics in a lot more detail. HOW DO WE KNOW WITHOUT TESTING? So, how do we know that a Smoke Barrier will limit the passage of smoke? Mostly, this is addressed by continuity. The assembly is required to be continuous and limit openings which would provide a pathway for smoke. Smoke Barriers and Smoke Partitions can be constructed of any material that’s permitted by the Construction Type for the building. Most often, they are simply gypsum, but other materials could be used. More than likely, the Smoke Partitions will be constructed of materials that’s used elsewhere in the building for a generic wall partition, except that it will need to be constructed continuously, with no unprotected openings, so that it can perform its task of limiting the transfer of smoke. SUMMARY So, what is a Smoke Barrier? A Smoke Barrier is like a heavy-duty version of a Smoke Partition. A Smoke Barrier carries the same requirements as a Smoke Partition, except that it must also be at least 1-hour fire-rated, and have supporting construction that’s at least 1-hour unless we meet exceptions. Our next part of this series in a recap crossword puzzle to test your recognition of the concepts we’ve talked about thus far in this series. After that, we’ll pick up with fire-ratings and smoke-resistance requirements for floor construction. I’m Steven Barrett, this is MeyerFire University.
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