Video: Correcting the Top Five Hanger Installation Errors
Originally published by: MiTek USA — April 4, 2017
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Steel hangers and connectors are often installed wrong, with incomplete fastener schedules, the wrong fasteners, and compromised bearing surfaces. This illustrated article looks at the top five hanger/connector installation problems… and how to fix them.
Joist hangers, hangers use for stringers and glulams, 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 the errors: The number of fasteners used is often incorrect; the wrong fasteners are used (undersized or oversized); and 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.
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.
Here 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.
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.
Shear Nails Missing
Shear nails missing. The hanger has no double shear nails, so it offers a reduced downward load and no uplift resistance at all.
A classic undersized hanger. Hanger height must equal at least 60% 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.
About MiTek: MiTek is a diversified global supplier of software, engineered products, services, and equipment to the residential, commercial, and industrial, construction sectors. MiTek Builder Products, a division of MiTek USA, integrates a number of businesses, building products, and brands, including USP Structural Connectors, the Z4 Tie-Down System, and Hardy Frame, as well as design software solutions for decks. Visit www.mitek-us.com