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Do Support Beams Within a Rated Stair Enclosure Require Fire Protection?

jar546

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In a recent analysis, I explored whether support beams within a stair enclosure in a Type IA building require fire protection. This building features an interior exit stairway positioned at a corner, with the exterior composed of non-rated curtain walls. Notably, inside these walls, HSS steel beams are exposed, providing support to the curtain wall and the intermediate stair landings. It's important to highlight that these beams don't bear the load of any floors, the roof, or the 2-hour fire barriers that form the interior side of the stair enclosure.

According to my understanding, based on the 2018 International Building Code (IBC) Section 704.1, fireproofing these beams isn't necessary. This is because they are located within the rated stair enclosure and don't support floor landings. However, I sought to confirm this interpretation to ensure accuracy.

An official opinion from the International Code Council (ICC) provided clarity on this matter. The ICC stressed that the stairway walls must be rated in accordance with the building's construction type, as outlined in 2018 IBC Table 601. Furthermore, Section 1011.7 of the IBC mandates that all stairways should be constructed from materials suitable for the building's construction type. The key takeaway here is that while structures supporting the stairway and its enclosure must adhere to fire-resistance ratings consistent with the building type, the stairway components inside the enclosure, such as intermediate landings, aren't held to these same requirements. In essence, intermediate landings aren't regulated like floor construction, and there's no code stipulating that they need to be rated.

The ICC's perspective is that the exposed HSS steel beams don't require individual protection, as they aren't serving as primary or secondary frame members. However, it's important to note that if beams are directly attached to columns that support the stairway stringers and the floor, then they are considered part of the primary structural frame. In such cases, as defined in Section 202, these beams and columns must have a fire-resistance rating that aligns with the building's construction type.

On the other hand, if beams and columns solely support the intermediate stairway landings, they aren't required to have a fire-resistance rating for the landing or its supports. This information provides a comprehensive understanding of the fire protection requirements for support beams within a rated stair enclosure, particularly in the context of a Type IA building.
 
“with the exterior composed of non-rated curtain walls.”

How can the stair enclosure be rated if 2 of the walls are not?
 
It is rated because it is separated from the hazard, in this case the hazard is the rest of the building.
 
In a recent analysis, I explored whether support beams within a stair enclosure in a Type IA building require fire protection. This building features an interior exit stairway positioned at a corner, with the exterior composed of non-rated curtain walls. Notably, inside these walls, HSS steel beams are exposed, providing support to the curtain wall and the intermediate stair landings. It's important to highlight that these beams don't bear the load of any floors, the roof, or the 2-hour fire barriers that form the interior side of the stair enclosure.

According to my understanding, based on the 2018 International Building Code (IBC) Section 704.1, fireproofing these beams isn't necessary. This is because they are located within the rated stair enclosure and don't support floor landings. However, I sought to confirm this interpretation to ensure accuracy.

An official opinion from the International Code Council (ICC) provided clarity on this matter. The ICC stressed that the stairway walls must be rated in accordance with the building's construction type, as outlined in 2018 IBC Table 601. Furthermore, Section 1011.7 of the IBC mandates that all stairways should be constructed from materials suitable for the building's construction type. The key takeaway here is that while structures supporting the stairway and its enclosure must adhere to fire-resistance ratings consistent with the building type, the stairway components inside the enclosure, such as intermediate landings, aren't held to these same requirements. In essence, intermediate landings aren't regulated like floor construction, and there's no code stipulating that they need to be rated.

The ICC's perspective is that the exposed HSS steel beams don't require individual protection, as they aren't serving as primary or secondary frame members. However, it's important to note that if beams are directly attached to columns that support the stairway stringers and the floor, then they are considered part of the primary structural frame. In such cases, as defined in Section 202, these beams and columns must have a fire-resistance rating that aligns with the building's construction type.

On the other hand, if beams and columns solely support the intermediate stairway landings, they aren't required to have a fire-resistance rating for the landing or its supports. This information provides a comprehensive understanding of the fire protection requirements for support beams within a rated stair enclosure, particularly in the context of a Type IA building.
Would it be possible to share the ICC opinion? This question has come up and I was leaning on the idea that landings had to be rated, because they support the stair, but that the stair themselves did not. Admittedly, I was/am conflicted by this, because I can't reconcile why the landing is more important than the stair itself. I was basing my thinking on the commentary to 1011.7. The ICC folks usually call me to discuss these types of issues, so if they didn't provide any written opinions I get it. If they did it would just be helpful. To me the opinion isn't perfectly consistent with the commentary opinion, but that happens sometimes.

In keeping with the different levels of fire protection
provided by each of the five basic types of construction
designated in Chapter 6, the materials used for
stairway construction must meet the appropriate combustibility/
noncombustibility requirements indicated in
Section 602 for the particular type of construction of
the building in which the stairway is located. This is
required regardless of whether the stairway is part of
the required means of egress. Any structure supporting
the stairway
and the stairway enclosure must be
fire-resistance rated consistent with the construction
type;
however, the stairway components inside the
enclosure need only comply with the material limits
for
the type of construction
 
It has been suggested that landings in a stair core are not floors as shown in t601, and therefore not subject to the fire-resistance requirements of that table, nor are stairs, because they aren't listed in t601. I am not sure how a landing isn't some type of floor, and I'm not sure what/how a stair would be considered. Some logic dictates that you are in a protected exit enclosure so the same requirements don't apply. Other logic says that the stair system needs to maintain its structural integrity for as long as the floors outside the stair core. I think we have a little conflict in the codes between t601 and 1011.7, and contradictory commentary.
 
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