Table 601/602 EXTERIOR bearing and non-bearing walls

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    David Kaplan

    Jon,

    In a nutshell, you are correct.  Generally speaking there are two main reasons you'd rate an exterior wall:

    1) Table 601 per the Construction Type.  If the Construction Type of your building requires it, you gotta do it.

    2) Fire separation distance - this really applies to ALL exterior walls, not just non-load bearing walls.  Using your given construction type and use group, you look at how close you are to a property line and determine from Table 602 if exterior walls are required to be rated.

    Hope that helps.

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    Jonathan Chertok

    hi david.
    ok. but for purposes of the exam all anyone needs to know in chapter 6 is to read the TYPE at the top row which will be given, and to roll down to BEARING WALL > EXTERIOR (or interior BEARING WALL) and read the hourly fire rating.
    /or/ to go down to FLOOR CONSTRUCTION or ROOF CONSTRUCTION and read the hourly fire rating.
    i was thinking there is NEVER a case where you refer to table 602 but in real life if you are asked for EXTERIOR NON-BEARING WALL you would have to refer to 602 which could have a /lower/ value for a NON-BEARING /exterior/ wall.
    i mean - you never refer to 602 unless you are looking at a NON-bearing wall and i’m guessing you would not have to determine this within the confines of the software and the time limit. but this is sort of anyone’s guess?
    table 602 is titled “exterior walls” but commentary says 602 refers to exterior BEARING and NON-BEARING! but 601 has a rating for BEARING exterior walls. and it is /always/ higher than 602.
    BUT if you were asked about a NON- bearing exterior wall 602 would have a value lower than if you picked the value from 601. do you follow? 601 specifies bearing walls but refers to 602 for NON-bearing walls. 602 states it is for bearing and non bearing but can never modify bearing wall value in 601. BUT if it is a non-bearing wall you have to use 602.
    this would be uber confusing in a timed exam with those ratchet drawings where you weren’t specifically told it was a bearing wall and even if you were it would be sort of confusing.

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    Jonathan Chertok

    i can’t edit on the phone.
    just a clarification: you are always going to rate the components of your building per 601 but you only go to 602 if you have a non bearing exterior or interior wall where the row in 601 /specifically/ refers you to 602 /or/ if the “sub-notes” from 601 refer you to 602 i suppose.
    but in all cases a bearing wall is read straight off 601.

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    David Kaplan

    Here's the 100% correct assessment of this.  I've done this exact exercise for 10 years:

    1) All exterior walls - you look to Table 602.  I don't care what they are, load bearing or not.  Table 602 applies to all exterior walls.  Period.  Finito.  Hasta Manana.  I'm 1,000,000% certain of this.  Go to that table first and based on your Use Group and Construction Type and your fire separation distance, find the rating requirement.

    2) Now, go back to Table 601.  If you in fact have exterior bearing walls in your building, check this table and see if a rating is required for them. 

    3) If a rating IS required, and it's higher than the one you just checked on Table 602, then you must go with the higher rating.  If it's lower than the one you just checked on Table 602, then you still must go with the higher rating.

    4) If a rating is NOT required, or you don't have any exterior bearing walls on your job, then you just go with Table 602.

    5) The verbiage in both tables referencing each other is the code telling you that the "most stringent requirement applies." 

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    Kurt Fanderclai

    David, good synopsis.  It'd be helpful if only your part could remain on the thread.  For the sake of other testers, the rest really should be deleted.  

    I had recently suggested to another candidate that if anyone happens to be struggling to this extent with the code, grabbing  some in-house project sets at the workplace and recreating the basic code review for each is a great way to "up" one's code knowledge pretty quickly.  At most firms, there is a person (or persons) quite happy to answer a few questions.

     

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    Jonathan Chertok (Edited )

    hi david.

    thanks. also sorry. i just want to make sure i understand this for the exam. can i use an example please?

    say i ask you to rate an EXTERIOR WALL. i provide Type IIIB and Occupancy M. i ask you to rate the "exterior" wall.

    if you refer to 601 it states Type IIIB EXTERIOR BEARING WALL is 2 hour rated construction. note F on EXTERIOR BEARING WALLS states that "Not less than the fire-resistance rating on fire separation distance (see Table 602)."

    but in 602 for ALL OCCUPANCIES M, A, B and E - and for ALL Fire Separation Distances - the required ratings are /less/ than the 2 hour rating provided in 601. so for all intents and purposes we can IGNORE 602 because 601 rules with the most stringent requirements. the only case 602 alters 601 is for certain Fire Separation distances for H Occupancy (and i'm pretty sure this won't be on an exam).

    HOWEVER, if i ask you to rate a /NON-BEARING/ EXTERIOR WALL, 601 refers you directly to 602. note A on 602 generically states that  "Load bearing exterior walls shall also comply with the fire-resistance rating requirements of Table 601." but as we have already seen, we can rate an exterior LOAD-BEARING wall in 601 (for all Occupancies except H) and we don't need 602.

    so now you rate an EXTERIOR /NON-BEARING/ WALL.

    in this case (for Occupancy M, Type IIIB) the wall is rated:

    less than 5': 2 hour

    5' to 10' ("Others"): 1 hour

    10' to 30' ("Others"): 1 hour

    greater than 30': 0 hours

    -

    from my reading this means that an EXTERIOR WALL, Occupancy M, Type IIIB is:

    2 hour for any EXTERIOR BEARING WALL

    2 hour for any EXTERIOR NON-BEARING WALL less than 5' separation

    1 hour for any EXTERIOR NON-BEARING WALL 5' to 10' separation and

    0 hour for any EXTERIOR NON-BEARING WALL greater than 30' separation

    and the answers provided are ALL different in all cases between an exterior BEARING WALL and an exterior NON-BEARING WALL, except in the case where the exterior NON-BEARING wall is less than 5' separation.

    i mean, what i am trying to make sure of is that you need to determine if the wall is bearing or if it is non-bearing up front to provide a correct answer - in addition to knowing the fire separation distance. but you only get into fire separation distance if the wall is non-bearing.

    does that make sense? it's confusing and in the context of a timed exam i think it could be super confusing for a lot of people.

     

     

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    Jonathan Chertok





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    Jonathan Chertok

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    David Kaplan

    Jon,

    100% correct.  Everything you've analyzed is right.  Only thing I noted, you forgot to mention the rating requirement for when you're between 10' and 30', which in your IIIB/Use M scenario is also 1 HR per Table 602. 

    At the end of the day, the Code is just trying to make sure that you reference both tables and just make sure you take the most stringent requirement.  You are correct that Table 601 only has ratings for exterior bearing walls, so if you have that, you have to make sure you look at that Table too.  For all non-bearing exterior walls, Table 602 is your go-to.

     

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