Z Clip Load Rating
Introduction
One of the most frequent requests at Monarch Metal is for the load bearing information of our Monarch Z Clip Systems for installing panels, signs and art work. In all of the internal tests Monarch has done, it has been the screws holding the Monarch Clips that fail and not the Monarch Clip itself. However, the question has come up frequently enough that we engaged Qualtim, Inc., a third party independent laboratory, to perform testing on the clips.
Testing Design
As part of the test design, we set out with the goal to understand what the mode of failure and relative strength would be for the most common installations. To understand the mode of failure, one has to start with the elements that are important to determining the strength of the system. The 5 elements to consider are:
1. The mounting surface for the continuous lengths. For example, will they be mounted to wood studs or metal studs? Will there be blocking? Drywall?
2. What screw is being used to mount the continuous length? Is it a sheet metal screw, a wood screw or a specialty screw? How long is the screw? What is the diameter?
3. Which Monarch Clip is being used? Stainless Steel or Aluminum?
4. What is the material, thickness and size of the item being hung?
5. What screw is being used to mount the shorter panel clips to the back of the panel?
About Questions
We only give all of these questions to illustrate the number of variables to control for when testing and show the difficulty of designing an appropriate test. These variables do not even include the typical variables to consider such as the environment of the installation as well as the direction of the force (assumed to be entirely in shear in this testing.)
3 Different Tests
- The first test was designed to test the load at which the Monarch Z Clips pull out from the backside of the panel.
- The second test was designed to test the load at which the system would fail in a standard installation of a ¾” thick MDF veneered panel onto steel studs with ¾” OSB blocking.
- The third test was designed to test the load at which the system would fail in a standard installation of a ¾” thick MDF veneered panel onto wood studs with ½” gypsum sheathing.
Standard Installation
A standard installation of a ¾” Thick, 48″ Wide x 60″ Tall MDF panel, involves mounting three different continuous lengths along the wall parallel to the floor. The continuous lengths would be spaced approximately 30″ apart. The continuous lengths are fastened to studs at a minimum of every 16″ on center with the appropriate screw. Our testing was done with 22 Gauge Metal Studs and Wood Studs and the results would not apply for weaker substrates.
Installers often use ¾” blocking in front of the wall to allow for added fasteners every 8″ on center along the wall. Along the panel, installers would typically use 12 panel clips on the back of the panel; 4 panel clips at each height to interlock with each of the 4 continuous lengths. These clips would be spaced 12 to 15 inches apart and fastened to the back of the panel with (2) #8x ¾” Pan Head Deep Thread Screws for a total of 24 screws in a typical panel installation.
Test Set-Up 1
Shear Test of Panel Clips
The first test formation was designed to test the shear strength of the panel clips mounted to the rear side of the panel. The continuous lengths were prevented from failing by reinforcing the wood studs with SPF 2 x 4 blocking and fastening the continuous length to the blocking every 4 inches.
Test Set-Up 1 – Conclusion
In these conditions where we controlled the set up to test only the Monarch Clips attached to the rear side of the panels, the panel failed at an average of 8,318 pounds. There were (24) #8 x 3/4″ pan phillips deep thread screws securing the (12) Monarch MF375 Clips to the back of the panel. The load per screw where shear failure occurred was 347 pounds. It is important to note that the Monarch Z Clip’s themselves did not fail at this load.
Test Set-Up 2
Standard Installation on Metal Studs with Blocking
Test Set-Up 2 – Conclusion
panel, forcing them to pull out. (24) #8 x 3/4″ pan phillips deep thread screws were used to secure the (12) Monarch MF375 Clips to the back of the panel. The load per screw where shear failure ocurred was 177 pounds. It is important to note that the Monarch Z Clip’s themselves did not fail at this load.
Test Set-Up 3
Standard Installation on Wood Studs with Gypsum
Test Set-Up 3 – Conclusion
back of the panel, forcing them to pull out. There were (24) #8 x 3/4″ pan phillips deep thread black oxide screws securing the (12) Monarch MF375 Clips to the back of the panel. The load per screw where shear failure ocurred was 167 pounds. It is important to note that the Monarch Z Clip’s themselves did not fail at this load.