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Stair egress capacity problem in existing high rise building

Discussion in 'Existing Buildings Codes' started by Tim Mailloux, Feb 12, 2018.

  1. Tim Mailloux

    Tim Mailloux Active Member

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    I am working on a renovation in an existing high rise, type 2A construction, for a local universities downtown campus. The existing floor plan consists of 5 large classrooms and a couple of small offices and a conference room. We are going to be demolishing one of the classroom and the existing offices and making a new office suite with a mix a new offices and conference rooms to support the remaining (4) classrooms. While our project area is only about half the existing floor plate I have calculated the occupant loads of the entire floor (renovated & non-renovated areas) and the total occupant load is 60 people larger than the existing stairs egress capacity as calculated by current Connecticut Building code. I have also calculated the occupant load of the existing floor plan with the (5) classrooms and the occupant load calculates out to be 80 people larger than the existing stairs egress capacity as calculated by current Connecticut Building code.


    Is there any leeway in the Existing Building code to make the argument that while the proposed occupant load exceeds the existing stair egress capacity, the new occupant load is lower than the existing occupant load thus making a bad situation better, but still not up to code?
     
  2. cda

    cda Sawhorse

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    Well

    No code section, but the city/ university accepted the exiting as is.

    Only thing the occupant load calc originally may have been different than what you calc
     
  3. Sifu

    Sifu Gold Member

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    That's a tough one. I face this type of thing very often. We have a lot of buildings that don't meet the codes under which they were originally constructed. Mostly, we make them upgrade.......but there are limits to what we make them do. It really stinks to tell an owner that the building they were told was acceptable really wasn't. These buildings are the most frustrating set of problems I face on a day to day basis. I don't know for sure it will help but you might look at the compliance alternatives. I have only ever had one applicant go that route, and it did give alternatives in his case.
     
  4. cda

    cda Sawhorse

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    If the stairs get brought up, you can always ask for a smaller assigned occupant load.
     
  5. Tim Mailloux

    Tim Mailloux Active Member

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    A constant issue I run into here in CT are existing stairs. The model IBC allows for stair egress capacity of .3 inches per person in non sprinklered buildings and a stair egress capacity of .2 inches per person in sprinklered buildings. The state of CT has a code amendment making the stair egress factor .3 inches per person regardless of sprinklers. If I could use the .2 factor from the model IBC I would rarely have this type of issue.
     
  6. Tim Mailloux

    Tim Mailloux Active Member

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    The CT State Building code doesn't allow for an occupant load lower than calculated by table by table 1004.1.2 to be posted. The occupant load per 1004.1.2 is the minimum occupant load of the room / space. Your occupant load can be higher, but never lower.
     
  7. Tim Mailloux

    Tim Mailloux Active Member

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    I will look into the compliance alternatives. Its been a very long time since I went that route on a project.
     
  8. cda

    cda Sawhorse

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  9. Tim Mailloux

    Tim Mailloux Active Member

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    The 2016 CT State Building Code is based on the 2012 IBC with amendments. CT deleted the exception to 1004.5 that allows the AHJ to assign a lower occupant load than calculated by table 1004.1.2.
     
  10. Francis Vineyard

    Francis Vineyard Sawhorse

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    Just asking;
    1) the conference rooms are reserved for office and classrooms; thus the occupant will not increase but moves from space to another similarly with school cafet?
    2) similarly with schools this is a single tenant space? The provision for Level two (2) means of egress "shall be limited to work areas that include exits or corridors shared by more than one tenant within the work area"

    The following (2012) sections can be avoided when the work area is 50% or less:
    803.2.2
    803.2.3
    803.4.1
    804.2.1.1
    804.4.2
    805.4.2.1
    805.4.3.1
    805.4.4.1
    805.5.3.1
    805.7.2
    805.8.2

    There may be other exceptions depending on the work area (see definition limited to the permit).
     
  11. Tim Mailloux

    Tim Mailloux Active Member

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    1) what you are referring to here is the concept of Non-simultaneous occupancy, which is not recognized by the IBC or the state of CT. In CT the state building official will only allow Non-simultaneous occupant load calculations to be used for plumbing fixture calculations in certain occupations, but never for life safety.

    2. Regardless of the size of the work area I need to prove I can get all the occupants off the floor. Are you saying that as long as a renovation does not exceed 50% of the floor area I could add 200 people to the occupant floor occupant load and wouldn't matter?
     
  12. cda

    cda Sawhorse

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    Are you sure you are in the USA

    We have rights
     
  13. mtlogcabin

    mtlogcabin Sawhorse

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    So are you using 20 net for the classrooms or something else such as assembly?

    For an existing building the posted OL should be the most restrictive along the egress path not what the room or floor will accommodate based on a supposed use. In your case it is .3 for the size of the existing stairs.
    If you check the legacy code the building was built under it was more than likely .3 for stairs back in the day
     
  14. ADAguy

    ADAguy Sawhorse

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    Who owns the building, university or private? If university owned it may have some leeway to self determine.
     
  15. Francis Vineyard

    Francis Vineyard Sawhorse

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    Appreciate learning new words to my nomenclature! How about the exception to 1004.1.2?

    Wouldn't that amount of increase be a change of occupancy applicable with Chapter 10?
     
    #15 Francis Vineyard, Feb 12, 2018
    Last edited: Feb 12, 2018
  16. Francis Vineyard

    Francis Vineyard Sawhorse

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    I overlooked this explanation and references between different code editions.

    My understanding for providing alteration thresholds before adoption of the IEBC with the prescriptive methods is code officials were inadvertently causing buildings to be limited to repairs or become vacant by requiring the complete structure to comply with the provisions of the current codes for new construction.
    This was cost prohibitive and sometimes technically infeasible to allow alterations .
    As mentioned it's often found the existing occupant loads exceed both the current code and the code when the occupancy was first permitted.
    And as previously pointed out the current code is limited to the "work area" as applicable.
    Depending on the code CT adopted typically should not have to retrofit until it meets a special provision for a change of occupancy.
     
    #16 Francis Vineyard, Feb 13, 2018
    Last edited: Feb 13, 2018
  17. Tim Mailloux

    Tim Mailloux Active Member

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    Francis, thanks for the explanation.

    So what your saying is that as long as there is no change of occupancy to the work area, the new occupant loads are not a factor in egress?

    Also, digging deeper into IEBC section 805 Means of egress, that section seems only to apply to multi-tenant floors. My project is a single tenant floor so section 805 does not apply, but section 704 Means of Egress does apply.

    704.1 General: Alternations shall be done in a manner that maintains the level of protection for the means of egress (could the ICC be any more vague? This leaves a lot open for interpretation).

    704.2 (CT Amendment) Minimum Standards: in addition to the requirements of this code, means of egress in existing buildings shall meet the requirements of the provisions of Part IV of the CT State Fire Safety code for the proposed occupancy.

    Part IV of the CT State Fire Safety code is 2012 NFPA 101 (with CT amendments) and it only applies to buildings built prior to 2005, which is when CT switched from BOCA to the IBC based code. Any buildings built after 2005 (under the IBC based codes) fall under part III of the CT State Fire Safety code witch is the 2012 IFC with CT amendments. Looks like I need to dig into the this a little more.
     
  18. mtlogcabin

    mtlogcabin Sawhorse

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    IEBC
    CHAPTER 14
    PERFORMANCE COMPLIANCE METHODS

    1401.2 Applicability.
    Structures existing prior to [DATE TO BE INSERTED BY THE JURISDICTION. NOTE: IT IS RECOMMENDED THAT THIS DATE COINCIDE WITH THE EFFECTIVE DATE OF BUILDING CODES WITHIN THE JURISDICTION], in which there is work involving additions, alterations or changes of occupancy shall be made to conform to the requirements of this chapter or the provisions of Chapters 5 through 13. The provisions of Sections 1401.2.1 through 1401.2.5 shall apply to existing occupancies that will continue to be, or are proposed to be, in Groups A, B, E, F, M, R and S. These provisions shall not apply to buildings with occupancies in Group H or I.

    We use the adoption date of the 2003 IBC. It works very well with older building and achieving compliance with the "intent" of the code.

     
  19. Francis Vineyard

    Francis Vineyard Sawhorse

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    701.2 Conformance. An existing building or portion thereof shall not be altered such that the building becomes less safe
    than its existing condition.

    To reiterate; 'alterations shall not make the existing building less safe than its existing condition"
    Comparison is made to the "existing condition" - not something that some past code might have required or "as required under the code in which it was constructed"

    Hope the above is helpful with the CT amendments.
     
  20. Paul Sweet

    Paul Sweet Sawhorse

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    When was it built (or last remodeled), and what code was it built (or remodeled) under? Were any code modifications granted when it was built or remodeled?
     

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