How to Connect Unistrut to Bar Joists

One of the things that makes Unistrut such a great option for so many applications is its adaptability and ease of installation, whether in a new structure or an existing environment. No matter how your facility is constructed, there is a way to securely install your Unistrut solution. One common question we get from clients is how to connect Unistrut to bar joists. Let’s go over your options and introduce you to Unistrut Midwest’s preferred method, using beam clamps.

If your facility’s ceiling is supported by bar joists (or open web steel joists) it may seem like it will be trickier to connect your Unistrut system than if you were working with something like beams. But you have a few options depending on variables like existing systems and barriers (mechanical, electrical, plumbing, etc.) and the preference or request of your engineer.

Threaded Rod Connection

Your Unistrut system will typically connect to your bar joist at the bottom chord. If you have an obstruction, such as a conduit or pipe running along the joist at the bottom chord, then you can use a threaded rod and washer to connect into the bottom chord. Check the diagrams below for a detailed look at a threaded rod connection. 

Joist Wrap Connection

There are situations where, due to too many obstructions or engineering requirements, you cannot connect Unistrut to the bottom chord of your bar joist. In this case, you’ll need to transfer the load to the top chord. The best way to achieve this is with a joist wrap connection. As the name suggests, this method wraps the bar joist in channel to properly distribute the load. The following diagrams show this method in detail. 

Beam Clamp Connection

Finally, the preferred method at Unistrut Midwest is the beam clamp method. This method uses joist clamps (also known as window clamps) and u-bolts to attach channel of any height above or below the bottom chord of your bar joist. Which clamps and bolts you need will depend on the flange of your bar joist, the size of your Unistrut channel, and the load requirements of your structure. While the clamp and u-bolt can be adjusted to adapt to different sizes of joists and channel, there are specifications that need to be considered. For example:

• P2785 is for use with channels P1000, P1100, P2000, P3000, P3300, P3301, P4000, P4001, P4100, and P4101
• P2786 is for use with channels P1001, P1101, P2001, P3001, P5000, and P5500
• P2787 is for use with channels P5001 and P5501

The diagram below shows how the beam clamp connection works. 

The Unistrut Midwest team is available to answer any questions you may have about the best way to connect Unistrut to your bar joists. Whether you are still weighing your options or are ready to place an order, our team is here to help.