minimum stairway width

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    Jonathan Chertok

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    Jonathan Chertok



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    Anson Nickel

    Hi Jonathan,

    It looks as though you are comparing accessible means of egress and what I'll call for now, regular means of egress. Stairs that are part of an accessible means of egress require additional width for rescue assistance (48" by code), unless the building has sprinklers, in which case stair width is governed by Section 1011

    As mentioned above, regular means of egress is governed by Section 1011 and starts with a baseline of 44" and provides for various exceptions. 

    Hope this helps,

    Anson

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    Jonathan Chertok (Edited )

    hey anson,
    so, just for the purposes of 2012 for sizing egress components - say stair or door (sorry i should have mentioned this) for the exam can you tell me where the minimums are listed for stairs and for “other egress components”?
    having 2015 and studying for 2012 is like a nightmare but being able to work a real example from the code commentary is quite nice (and helpful and practical etc).
    i mean, if i run the calculations per 1005.3.1 Stairways or 1005.3.2 Other Egress Components - where is the check against minimum requirements in he 2012 code again?
    and is there a lowering of this minimum standard for sprinklers? /or/ is the lowering i see in 1009.3 in 2015 code with respect to stairway minimums (1009.3) when the building is sprinklered irrelevant for the needs of sizing egress components.
    again apologies but the examples provided in 2015 commentary are for the most part excellent. but cross referencing them (when this happens) is a nightmare...

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    Jonathan Chertok

    also (thanks and sorry) but is there another citation for the 48” minimum you cite? 1011 in the code i printed out from the software is saying this is Illumination...
    THANK YOU

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    Anson Nickel

    Using IBC 2012 citations, Sec. 1005.2 states "The minimum width, in inches, of any means of egress components shall not be less than specified for such component, elsewhere in this code." - This is a reference link to the rest of Chapter 10 (Sec. 1008 - Doors, Sec. 1009 - Stairways, etc).

    All Sec. 1005.3 does is give you the tools to calculate the required dimensions based on your occupancy. You would then need to check those calculations against the remaining sections, per Sec. 1005.2

    As for downsizing if the building is sprinklered, the 48" minimum accessible width would then revert to whatever Sec. 1009 mandates.

    IBC 2012 1007.3 refers to the minimum width of 48" in accessible means of egress.

     

    Hope this helps,

    Anson

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    Jonathan Chertok

    ooh boy. thanks a ton.
    so, 1005.3.1 Stairways (or 1005.3.2 Other Egress Components) then reference 1009 Stairways (2012 code) and 1009.4 Width (44”) (or 1008.1.1 Size of Doors).
    in 2015 Secrion 1009 is Accessible Means of Egress (which is more than a tad confusing).
    so - can i just ask this even though it is not on the exam or at least i sincerely hope) - the 44” minimum is as specified in the code is dependent upon the calculation not being larger.
    the 48” is if you deem the Exit Access accessible (or need to?) and 48” rules in the case of non-sprinklered occupancy for an accessible corridor? in the event the building is sprinklered you can go somewhere between 44” and 48” per some other section of the code?
    again thanks for the citations and the bail out.
    APPRECIATE IT

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    Anson Nickel

    Correct. 

    Note that the calculations in 1005 are the TOTAL amount of egress width for whichever component. The sections further down (1008, 1009, etc) are for minimum widths at INDIVIDUAL components of egress. 

    Example: You have 440 occupants on a floor in a sprinklered building, you would need 440 * .3 = 132 in of stair width. Because of the sprinklers, you don't need to abide by the 48" minimum of 1007. Instead, you would go to 1009 and find that the minimum per stair is 44". 

    Therefore, you would need 3 stairs at 44" wide each (3 * 44 = 132). You couldn't have, say, one stair at 32" wide and two stairs at 50" wide each. Although you'd have the required TOTAL width, one stair would not be code compliant.

    Note again that all these citations are for IBC 2012. 

    Hope this helps,

    Anson

     

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    David Kaplan

    There's a prime example of this in the ARE Handbook sample exam.  The question about calculating the size of the door and the width of the stair.  That's a primo example.  You can do that - you're good to go. 

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    Jonathan Chertok

    looks like 1011 for Stairways is the citation in the 2015 code with 1011.2 being Width and Capacity. Size of Doors for 2015 is under 1010.1.1 for all the future lurkers.

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    Jonathan Chertok

    hi anson. nice. thanks.
    so other than the fun 2012/2015 code discrepancies - from the sounds of your answer it seems that specifying a building as /sprinklered/ allows us to use the minimum 1008.1.1 (Doors etc) or 1009.4 (Stairway) width?
    but if the building was called out as non-sprinklered we would have to step up to the 48” specified elsewhere in 10 (at least for stairway clear width)?
    have i got that right?
    THANKS again
    jon

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    David Kaplan

    Jon,

    No, I would not agree with that.  To Anson's point above, the 48" rule only applies if you are designing your stairs as an "accessible means of egress."  If you are not doing that, the 44" rule applies.  For reference, look at 1009.2 - they list several options for designing an accessible means of egress.  While fire stairs are probably the most widely used, it is not an absolute requirement and there are other ways to do it.  As such, for the exam, if you are not specifically told to design the stair as such, you should not assume that you should.

    Here's what I would expect on the exam if you get something like this: in the body of the question, the ARE will tell you if the stair in question is to be an accessible means of egress, and furthermore, they'll give you the code excerpt needed for it.  If you were NOT told in the question (like the one in the practice exam) that it is to be an accessible means of egress and they don't give you that excerpt, you should safely assume that you do NOT need to factor that in, and instead should only be using the code excerpt regarding stairway width calculation that they give you. 

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    Jonathan Chertok

    hi david,
    thanks again for your expertise.
    so if it doesn’t say it is an accessible means of egress one uses the 44” minimum (in the case of stairs) or the 32” minimum in the case of doors i guess.
    but if it is an ACCESSIBLE stair you need to use 48” minimum?
    i mean i realized on this one that if you remember 44” and 32” (and simply use these numbers if your manual calculation is lower) you won’t have to go hunting in the code for the minimum which will save you a minute or two.
    again likely not on the exams i suppose but there did seem to be something in there about the 48” only applying in the case of i sprinklered buildings. not sure though.
    THANK YOU
    jon

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    David Kaplan

    Correct, except that if it is an accessible stair and NOT sprinkled, THEN you use the 48" minimum between handrails rule. 

    I truly, truly do not believe that, if asked a stairway minimum width question on the exam, that you will not be expected to memorize any of this.  Thus, NCARB will give you the code excerpt, and if they only give you the one referencing the 44" rule, then you shouldn't need to worry about the 48" accessible means of egress rule.  They will tell you that or provide that excerpt if it needs to be taken into consideration. 

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    Jonathan Chertok

    got it. i guess i transposed the sprinkler issue in my text. thanks a ton.

    just in case anyone that runs the exam on 2015 IBC and is using the commentary, there is a typo in the problem sets. the notation to refer to 1009 is incorrect and this should be section 1011.1 as is correctly referred to later. 1009 is from 2012 IBC which everyone was kind enough to point out to me here...

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    Bahri Ozaslan

    Hello,

    I am confuse about stair which is an part of accessible means of egress. What makes the stair is part of the accessible means of egress?

    I was thinking the meaning of accessible that can be used by disabled people.Since disabled people are NOT using stair in case of emergency what it's meant by saying accessible ? Is it just to provide area of refuge?

    In addition to that let's say building is NOT sprinkler, is one of the required means of egress should be accessible means of egress? and If the building is sprinkler there is no requirement for accessible means of egress?

    Can you please clarify for me?

    Thanks a lot.

     

     

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