Joist hangers, hangers used for stringers and Glu-Lams, truss hangers, and hangers used in decking and stairs are often installed wrong, and this compromises their ability to ensure the integrity of the structure, to say nothing of ensuring code compliance.
Top reasons for installation errors:
- The number of fasteners used is often incorrect
- The wrong fasteners are used (undersized or oversized)
- The bearing surfaces are not to spec
Here are the top five hanger installation errors that reps from USP Structural Connectors have seen in the field.
1. Improper Nailing of an I-joist
The side nail into the bottom flange of the I-Joist is installed at the wrong angle. This may cause splitting of the bottom chord.
The nail through the dimple should have been installed at a 30 to 45 degree angle.
Nails installed into the underside of the bottom chord are not necessary.
2. Improper Bearing (1:00)
In this photo, the carried truss is not fully bearing on the hanger seat.
Some gapping of framing members in a hanger is OK, but gaps greater than 1/8” are unacceptable and compromise the hanger’s specified capacity.
3. Improper Hanger (1:37)
The problem here is the use of a non-sloped hanger. (It is also installed with the wrong type of screws.) In this situation, use a sloped seat hanger, at left.
With a standard hanger, the wood is bearing only on the very front edge of the hanger. By using a hanger with a sloped seat you get full bearing of the wood in the seat of the connector.
4. Shear Nails Missing (2:06)
5. Undersized Hanger (2:31)
Hanger height must equal at least 60 percent of joist height.
This is a rule developed to deliver enough hanger capacity and lateral stability of the connection.
To fix this without tearing out the existing hangers, framing angles could be added above the hanger to add lateral stability.