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  1. #1
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    Default Baluster Deflection

    Hi folks,


    As I recall there is a requirement on strength of guardrails (I can't find it in the IRC). But, is there a strength requirement on the individual balusters? A friend is looking to use thin (1/4") steel pipe as the individual balusters, but the concern is deflection of the material.


    Presumably, this is some ASTM standard, but I don't have access to ASTM.

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  2. #2
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    Default Re: Baluster Deflection

    Gunnar,

    While there is no strength requirement for each or any given baluster, the balusters make the guard infill, and the guard infill is required to resist a horizontal load of 50 pounds per square foot (a square foot includes the balusters and the air between each) and not allow a 4" sphere to pass through.

    I don't have access to the codes right now, but the section is in the Live Loads table for design requirements.

    Jerry Peck
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  3. #3
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    Default Re: Baluster Deflection

    In the IRC, check Table 301.5, go down to guards for the top rail; next row down is guard in-fill components.

    Make sure to read the indicated notes, specifically note f.

    Jerry Peck
    Construction Litigation Consultant ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  4. #4
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    Default Re: Baluster Deflection

    Quote Originally Posted by Jerry Peck View Post
    Gunnar,

    While there is no strength requirement for each or any given baluster, the balusters make the guard infill, and the guard infill is required to resist a horizontal load of 50 pounds per square foot (a square foot includes the balusters and the air between each) and not allow a 4" sphere to pass through.

    In the IRC, check Table 301.5, go down to guards for the top rail; next row down is guard in-fill components. Make sure to read the indicated notes, specifically note f.
    Jerry,

    Thank you, that was very helpful.

    What I am thinking of (in part) is cable railings (or anything that can deflect past the 4"). Cable railings are (theoretically) less than 4" apart, but anyone with minimal effort can widen the opening greater than 4", even when they are well-tensioned. I have seen some where the cables were sagging and could be opened more than twice the original spacing because the cables were so loose, yet they were less than 4" apart (except between the top cable and the top cap of the guard.


    Using a different material as an example, 1/4" copper tubing on even 3" centers might withstand the 50 pounds per sq.ft. But, I bet a child could force their head through the opening because the tubing would be easy to push aside enough to allow a 6-7" gap.

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  5. #5
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    Default Re: Baluster Deflection

    Gunnar,

    Exactly why I always wrote those cable type in-fills up.

    One would likely be able to play 'Dualling Banjos' on those cable in-fills if they were tensioned enough to not separate enough and resist passage of a 4" sphere, or maybe only have a 2" spacing with the typical tension put on those cables - thar might still resist the passage of a 4" sphere.

    Jerry Peck
    Construction Litigation Consultant ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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