Using Stainless Steel Z Clips with GFRC Panels

GFRC is an acronym for glass fiber reinforced concrete panels. These panels can be used as cladding, curtain walls or veneers and have the benefits of lightweight, strong, durable and the ability to be molded into decorative shapes. The panels are pre-made in the factory, which can often speed up installation and insure a consistency across the panels.

GFRC has a flame spread of zero because it is made from non combustible materials and can offer a high level of wind resistance. The panels can be given textures like with a stucco, patterns such as a brick pattern and can also be colored.

There are a variety of ways to install GFRC panels, but we have had a number of inquiries recently about using GFRC panels with Monarch stainless steel z clips. Attaching the stainless steel continuous lengths to the wall is generally straight forward. The critical constraint to determine is how you plan to attach the stainless panel clips to the back of the GFRC panel. Monarch has not done any testing and can not offer any structural advice, but we can tell you what our customers have tried so that you can do your own testing. The choices are a tapcon screw with an epoxy adhesive, a concrete anchor and screw system or simply using an epoxy.

If you are going to use a Tapcon screw, you need to select the flat head concrete screw vs. the hex head. The reason is that the stainless steel z clip system only has .120” for the head of the screw and the hex head variety exceeds that dimension. To use the flat head concrete screws, the stainless steel z clips will need to be countersunk. You can choose to countersink them yourself or to have Monarch countersink them for you to simplify installation on the job site. Another important consideration for the concrete screws is the minimum and maximum embedment of the shank. Most of the manufacturers recommend a minimum embedment of the shank in the material of 1” and a maximum embedment of 1.75”.

If you choose to use an epoxy, we could suggest that you contact the manufacturer to discuss the appropriate adhesive for the conditions of the installation. You are going to want to pay extra special attention to making sure that you are able to control the environment of the installation for the cure period in order to have the adhesive reach its maximum strength. This can often mean pre-installing the stainless z clips in an internally controlled climate. You also want to clean the material with an abrasive cleaner to remove any oxidation and rough up the surface to create a stronger bond.

When using a concrete anchor and screw system (often used in addition to an adhesive), you are going to want to ensure that the head of the mechanical fastener you are using can fit within the height of the stainless z clips (.120”) and that the fasteners has the same durability as the stainless steel clips.