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Backer
blocks are used to fill the rectangular space
between the outside edge of the I-Joist flange and
the web of the I-Joist. The purpose of the backer
block is to provide aflat, flush surface by which
surface or top mounted hangers can be attached to
I-Joists.
With
face-mounted hangers, the backer block provides
anchorage for the hanger nails. It also provides an
avenue for the transferal of the hanger load to the
web of the I-joist. For such applications, backer
blocks on both sides of the web are almost always
required.
With
top-mounted hangers, the backer block prevents
rotation on the lower portion of the hanger by
filling the void between the hanger and the web. If
the top-mounted hanger does not rely on any
attachment into the side of the I-Joist supporting
it, as with face mounted hangers. The backer block
is only providing bearing for the bottom of the
hanger and an additional backer block on the other
side of the I-joist web is not required. |
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