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Re: Joist Tag Designations

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Joist tags are not guaranteed to contain anything of interest to an
engineer.  Typically they contain the manufacturer's name, contract
number, and piece mark.  Sometimes they also contain the joist
designation, but not necessarily.  In this case you may be right about
the 18J7 being the designation, but don't bet the farm on it.  72109 is
PROBABLY the manufacturers contract number, and  J-13 is PROBABLY the
mark number.  Regardless, the only way to be sure what you have is to
measure EVERY piece of steel in the joist (webs and sometimes chords
change sizes throughout the length of the joist), measure the welds, and
reverse engineer it to determine strength.  From 1961 it's probably A36

Phil Hodge

Zachary Goswick wrote:
> I have to check a joist built in 1961 to see if it can support some
> additional loading.  The joist tag said "18J72109J-13."  I know what the
> 18J7 means, can anybody enlighten me as to what the other numbers mean?
> Or possible direct me where to look?  Thanks.
> Zachary Goswick
> Angus-Young Associates, Inc.
> 555 South River Street
> Janesville, WI  53545-4827
> Phone: (608)756-2326
> Fax: (608)756-0464
> zachg(--nospam--at)