Is this another wrong question (example 14.2) from Ballast 5.0 Review Manual..?



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    Stephen Starks


    in my opinion...

    IBC section 506.3.2 seems to say that the value of "W" is 20 (as long as the actual distance is greater than or equal to 20 feet, but less than 30 feet). Remember, distances of over 30 ft. are handled in this way.

    If that is the case, Ballast's answer of 0.3 (0.33) would be accurate.

    However, according to the IBC 2015 code commentary this interpretation is inaccurate. The value of W is 24 feet based on the weighted average method found in section 506.3.2. Therefore, (((180 ft /240 ft) - 0.25)* 24 ft.) / 30 = 0.4 or answer D.

    Ballast's interpretation of code would seem to be inaccurate in this case (although you could make the argument to some code officials that this interpretation is acceptable - and win).

    As always though, check up on this yourself.

    Good catch!


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    Elif Bayram

    Hi Stephen! My understanding was same as yours, thanks for elaborating much better than I did.


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