I-Joists and Deflection
To the Editor:
I read with interest John
Siegenthaler's article "Wood I-Joist
Fundamentals" (Practical Engineering,
10/95). I am curious why the author
did not mention deflection in this article,
as this often controls in bending
John "Buddy" Showalter, P.E.
American Wood Council
John Siegenthaler responds:
The purpose of the article was to
illustrate to builders (who are often
more familiar with hefty solid-sawn
lumber) how an I-joist, with its thin
profile and light weight, can handle the
bending forces present in a floor joist.
Nevertheless, your point is a good one;
namely, that deflection — of either a
solid-sawn joist or an I-joist — is usually
the limiting factor in joist selection.
Most building codes allow