How to Attach Unistrut to Bar Joist with Threaded Rod

Unistrut channel is attached to the bottom chord of the bar joist - either above or below the chord. The channel and channel nut rest on one side of the chord, while on the other are the flat plate fitting and mounting hardware. The chord is sandwiched between the assembly components and a length of threaded rod runs through everything.

Download this Handy Connection Guide

UNISTRUT-JOIST-ROD: How to Attach Unistrut to Bar Joist Using Threaded Rod

Which Hardware and Fittings Should I Use?

The size of the threaded rod will determine what size hardware you will need. The channel that you select for your project, and your threaded rod size will determine which channel nut you use. In the example we have provided, we are using Unistrut P1001 double strut channel (1-5/8" x 3-1/4", 12 ga) and 1/2" threaded rod. Both of these are compatible with the Unistrut P3013 channel nut, which is designed to be used with 1-5/8" wide channel and 1/2"-13 threaded rod or hardware. All hardware in our example is 1/2"-13.

Assembly Components

A list of all the components appears below.  On one side of the bottom chord are the channel and the channel nut, on ther other side are the flat plate and the rest of the assembly hardware. Together these components snadwich the chord, with the threaded rod running through and connecting them all together. The channel can be mounted to either the top or the bottom of the chord.

There are any number of flat plate fittings, or plate washers that can be used or even fabricated to suit your needs. The components below are just examples of the types of channel, hardware and fittings that can be used in your assembly.

  • Threaded Rod (such as 1/2"-13 diameter) - slides through all channel, hardware and fittings

Bottom Joist Chord - Side One

  • Channel (such as P1001) - mounts to either top or bottom of bottom chord of joist along with the channel nut, opposite the rest of the hardware and fittings
  • Channel Nut (such as P3013) - to attach the threaded rod to the Unistrut channel

Bottom Joist Chord - Side Two

  • Plate Washer / Flat Plate Fitting (such as P1064) - a flat plate which sits flush against the bottom chord of the joist and has an appropriately size hole for your threaded rod to poke through. It bridges the gap / split in the chord - and therefore must be wider than the split - and provides a surface for hardware to mount to, as well as helps evenly distribute load. *wider opening in the chord will necessitate the use of a larger flat plate fitting*
  • Flat Washer (such as HFLW050) - goes on between the flat plate and the lock washer
  • Lock Washer (optional - such as HLKW050) - the lock washer goes on between the flat washer and the hex nut
  • Hex Nut (such as HHXN050) - the hex nut tightens the assembly together and holds all of the hardware in place on the threaded rod

Are There Other Methods of Attaching Unistrut to Bar Joist?

Yes there are! This is just one of three blog posts in our series on how to connect bar joist to strut channel. Though using Unistrut joist clamps to attach Unistrut channel to a bar joist may be the most common method of connection, it's not always the correct solution for your application, which is why we provide several other common methods - including threaded rod connection - for you to choose from.

Ultimately, the method that works best for your specific project may depend on a few key factors, such as:

  • What mechanical, electrical, plumbing and HVAC elements, or obstacles, are already in place
  • What has been requested by the project engineer

Other methods of Connecting Unistrut Channel to Bar Joist include:

  • Beam Clamps / Joist Clamps
  • Joist Wrap

RESOURCES

Installation

Download Connection Guide for UBS-JOIST-ROD
UBS-JOIST-ROD: Unistrut Bar Joist Threaded Rod Assembly (3.36 MB)

Submittals

Unistrut P1001 Product Submittal (344.95 kB)

Unistrut P3006 Product Submittal (313.70 kB)

Unistrut P1062, P1063, P1064, P1964, P2471, P2490 Product Submittal (305.17 kB)

Unistrut HFLW Product Submittal (315.74 kB)

Unistrut HLKW Product Submittal (318.13 kB)

Unistrut HHXN Product Submittal (320.46 kB)

Drawings

Unistrut BIM / CAD Library

DISCLAIMER

STANDARD DETAILS ARE FOR REFERENCE AND DESIGN PURPOSES ONLY, AND ARE NOT INTENDED FOR USE AS FULLY ENGINEERED SYSTEMS. ENGINEERED SYSTEMS MUST TAKE INTO ACCOUNT ACTUAL SITE CONDITIONS (SUCH AS: LOAD, ELEVATION, SIZE, SPACING, BUILDING STRUCTURE, EXISTING MEP STRUCTURES, ETC.) AND BE PURCHASED THROUGH UNISTRUT BUFFALO SUPPORTS, A DIVISION OF EBERL IRON WORKS, INC. 128 SYCAMORE STREET, BUFFALO, NEW YORK 14204. CONTACT UNISTRUT BUFFALO SUPPORTS: 1 (800) 285-3056 UNISTRUTSTORE.COM/REQUEST-QUOTE FOR A CUSTOM QUOTE TAILORED TO YOUR JOBSITE/PROJECT.