February, 2004
Technical Jargon: Joist
Hangers
“Technical Jargon” is a forum used to provide more information on terms commonly seen in U.S. Inspect reports.
Joist hangers are metal
fasteners used to support the joist where it connects with the beam or
perimeter joist. They serve to insure that the weight of the joist bears
properly on the beam. A joist hanger is a piece of sheet metal that is flat
on the bottom, to cradle the joist, and twisted on each of its sides so it
also sits flat against the beam. The hanger is then nailed to the beam.
There are several alternative joist end attachments, but most are less
reliable.
Toe nailing is a common way of connecting a joist to a beam. When the joist
is toe-nailed, the nail is driven at about a 45-degree angle through the
side of the joist end, into the beam. This can be unreliable if done
incorrectly because the structural load will not bear properly on the nail,
leading to eventual separation of the junction.
Joist
hangers address this vulnerability by insuring proper shear loading. Shear
load describes the way the structural load bears on the junction. Think of
it this way: You can break a pencil easily when you put your thumb in the
middle and bend it from each end. Now form a fist over each end of the
pencil and push your hands together. Pull straight back with one hand while
pushing forward with the other. It’s very hard to break the pencil at the
point in between your hands, isn’t it? The pressure that you are putting on
the pencil is a shear load.
Click
here for more information about joist hangers.
Contributed by Justin Gore
Quality Assurance Supervisor
U.S. Inspect, LLC
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