1. Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by clicking here: Upgrades
    Dismiss Notice

High-Rise Communicating Stair

Discussion in 'Commercial Building Codes' started by HVACQuestions, Sep 23, 2019.

  1. HVACQuestions

    HVACQuestions Registered User

    Joined:
    Sep 23, 2019
    Messages:
    5
    Likes Received:
    0
    HVAC designer here, I'm working on a job with an existing high rise tower with a communicating stair connecting 2 floors. The architect wants to cut another hole in the ceiling to have this stair connect 3 floors. I'm trying to figure out any mechanical implications of them doing so; is there a section of the IBC that governs fire protection/smoke concerns with communicating staircases? I thought it had to do with the size of the stair opening.
     
  2. RLGA

    RLGA Sawhorse

    Joined:
    Oct 18, 2009
    Messages:
    1,759
    Likes Received:
    554
    Which code edition year is applicable and what occupancy group is using the stairway?
     
  3. HVACQuestions

    HVACQuestions Registered User

    Joined:
    Sep 23, 2019
    Messages:
    5
    Likes Received:
    0
    I'm going off of IBC 2015, occupancy group B
     
  4. cda

    cda Sawhorse

    Joined:
    Oct 19, 2009
    Messages:
    16,597
    Likes Received:
    1,071
    Welcome
     
  5. RLGA

    RLGA Sawhorse

    Joined:
    Oct 18, 2009
    Messages:
    1,759
    Likes Received:
    554
    This would be an exit access stairway per Section 1019. You may be able to use Section 1019.3, Condition 4, as an option. If not, then the stairway will need to be enclosed,
     
  6. HVACQuestions

    HVACQuestions Registered User

    Joined:
    Sep 23, 2019
    Messages:
    5
    Likes Received:
    0
    Even though this stair is not a path of egress?
     
  7. HVACQuestions

    HVACQuestions Registered User

    Joined:
    Sep 23, 2019
    Messages:
    5
    Likes Received:
    0
    Thanks!
     
  8. RLGA

    RLGA Sawhorse

    Joined:
    Oct 18, 2009
    Messages:
    1,759
    Likes Received:
    554
    All stairways are part of an egress path whether intended or not. Openings between floors must comply with the requirements of Chapter 7 and it will have exceptions or conditions specific for egress elements per Chapter 10.
     
    HVACQuestions likes this.
  9. HVACQuestions

    HVACQuestions Registered User

    Joined:
    Sep 23, 2019
    Messages:
    5
    Likes Received:
    0
    Interesting. So a communicating stair that is not intended to be of use for egress, still has to comply with this section? It surprises me that this isn't handled similarly to an escalator opening.
     
  10. Tim Mailloux

    Tim Mailloux Registered User

    Joined:
    Feb 12, 2018
    Messages:
    156
    Likes Received:
    21
    I was under assumption that an unenclosed communicating stair which is not part of the egress system (exit access stair) is handled similar to an escalator.
     
  11. RLGA

    RLGA Sawhorse

    Joined:
    Oct 18, 2009
    Messages:
    1,759
    Likes Received:
    554
    Start first in Section 712 for vertical openings. It does have requirements for escalators—but escalators only. Other options in this section for this specific application include enclosing it in a shaft, making it an atrium, or making it an exit access stairway.
     
  12. steveray

    steveray Sawhorse

    Joined:
    Nov 25, 2009
    Messages:
    6,605
    Likes Received:
    904
    Ron has it....An opening with a stair in it is not always egress, but it is always a hole in the floor...And may or may not need to be protected....
     
  13. Tim Mailloux

    Tim Mailloux Registered User

    Joined:
    Feb 12, 2018
    Messages:
    156
    Likes Received:
    21
    Wouldn't section 712.1.9 Two story openings apply to this situation?
     
  14. cda

    cda Sawhorse

    Joined:
    Oct 19, 2009
    Messages:
    16,597
    Likes Received:
    1,071

    “””The architect wants to cut another hole in the ceiling to have this stair connect 3 floors“””
     
  15. steveray

    steveray Sawhorse

    Joined:
    Nov 25, 2009
    Messages:
    6,605
    Likes Received:
    904
    Yep...2 story is easy if no other "holes" to other floors...
     
  16. Tim Mailloux

    Tim Mailloux Registered User

    Joined:
    Feb 12, 2018
    Messages:
    156
    Likes Received:
    21
    I missed that part. Looks like the stair either needs to be classified as an atrium or an access stair. An access stair will be cheaper than an atrium (smoke control) as long as the travel distances will work.
     
  17. tbz

    tbz Silver Member

    Joined:
    Sep 10, 2010
    Messages:
    512
    Likes Received:
    17
    Interesting Topic, but I have another question on this topic as to location.

    • So currently there is a communicating stair from lets say 4th floor to the 5th floor.
    • Now lets say on the other side of the office space, not in the same location now wants to install a 2nd communicating stair from the 5th floor to the 6th floor, but neither stair flight or opening are in the same visual sight line, but open air will travel from one area to another.
    • does this change anything since they are 2 different stair flights and not stacked?
     
  18. RLGA

    RLGA Sawhorse

    Joined:
    Oct 18, 2009
    Messages:
    1,759
    Likes Received:
    554
    Compliance with 712.1.9 is required. Two-story openings are permitted, but item #6 of that section requires openings serving other stories to be separated by fire-resistive construction as required for shafts. Thus, since the two openings would technically connect three stories, then a 1-hour fire barrier is required on the 5th story somewhere that would completely separate the two openings from one another. If the floor assemblies are required to be of 2-hour construction or more, then the fire barrier separating the two openings must have a fire-resistance rating of 2 hours.
     
    #18 RLGA, Sep 25, 2019
    Last edited: Sep 25, 2019
  19. steveray

    steveray Sawhorse

    Joined:
    Nov 25, 2009
    Messages:
    6,605
    Likes Received:
    904
    Yep...Especially problematic in existing buildings where there may be nonprotected HVAC and other "shafts".....
     
  20. Builder Bob

    Builder Bob Sawhorse

    Joined:
    Oct 17, 2009
    Messages:
    2,187
    Likes Received:
    317
    Look at the technical report of MGM Fire - majority of fire fatalities was from smoke inhalation and not thermal or fire due to the ability of the smoke to easily transfer to the higher floors when the fire originated in the lobby/1st floor area.
     

Share This Page