Dec 5 2016   |   by Joel McKinely   |   Insider, ACM Systems, ACM Installation

The Use of Exposed Fasteners in Composite Panel Systems

With the composite panel industry ever changing and rapidly becoming more competitive each and every year, the necessity for ACM fabrication companies to attempt to accelerate the manufacturing processes has become a must to remain competitive and profitable. Unfortunately, one of the shortcomings we have found that's been allowed to take place has been the introduction of self-drilling screws or sheet metal screws into the manufacturing process, as opposed to using conventional structural rivets.

To our amazement, these types of fasteners have recently been utilized by many fabricators as a means of cutting down on manufacturing time and increasing production throughput. One of the faults that we see with the use of screws is that they are the furthest thing from being aesthetically pleasing and create a lack curb appeal on any finished project once panels are installed. More often than not, these manufacturers that are cutting corners and utilizing screws in assembly, are also not taking the time to countersink the screws on the ACM panels or color match their "panel fasteners", as they'll refer to them sometimes to match the chosen composite panel colors. In many instances they are also not utilizing a C&C routing machine to locate their fastener holes to ensure a uniform look and the screws or fasteners are simply rammed in by hand during the assembly process.

The obvious concern that arises when these “panel fasteners” are used is that attention must be focused on how these screws are installed. Without proper pull out data, or ensuring specific ft./lbs. of tightening torque during assembly, one would have to assume that they will be prone to loosening over time, as positive and negative air pressure and wind act upon the installed panels. Monitoring this concern with any means of quality control methods are often left in the hands of the assembler, who may decide when to stop pulling the trigger on a cordless drill.

Another concern is that during assembly, when you are setting the screw through the panel flange, you have a very small material contact point that is actually interacting with the perimeter extrusion. Quite often only a couple of threads on the screw are actually holding the ACM panel to the perimeter frame and it can be very easy to strip the fastener. Additionally, panel assemblers may not be countersinking the ACM panels before installing screws; they are simply crushing the core of the ACM panel while fastening it and this could potentially cause material warranty issues with the ACM panel system down the road.

Air and water infiltration or leakage issues can become obvious and we fail to recognize how, through the use of mechanical fasteners such as screws, that composite panels systems can pass stringent tests such as AAMA 508 pressure equalized rain screen criteria without the use of sealants on fasteners or doctoring of the test specimen to produce a passing result.

This does beg the question, "Has anyone stated that they have passed AAMA 508-07 Pressure Equalization testing, Water Penetration Resistance testingASTM Air Infiltration or Structural Performance standards, using these screws?" If you happen to come across a manufacturer who claims that they have structurally tested and rain screen tested their systems with screws, know that it is virtually impossible to have 20 to 30 screws passing through the perimeter of a single composite panel and have it meet pressure equalized rain screen testing criteria.

Can screws be utilized for wet joint systems? Yes, they are often used with wet joints applications because everything in the system is being buried behind backer rod and caulking once the install is completed. Unfortunately, you’ll never know if there are screws or rivets being used during assembly and these systems tend to lend themselves to low budget assembly techniques in an effort to offer a cheaper product. However, we are seeing more and more that screws are being utilized in a dry joint application. Seemingly, it is becoming an acceptable method and that’s concerning so that’s why we’re talking about it here. In our opinion, unfortunately, it is all to often simply a means of also selling a cheaper product and lowering margins through a lack of creativity and innovative solutions.

Efforts to expedite manufacturing are where these techniques often come into play. Although it may be true that by ramming a self-drilling screw through a composite panel you are able to increase your daily fabrication throughput to meet construction schedules, but it is by no means a preferred method. In our eyes, it can become a sub-standard product.

We would go so far as to say that there are in fact some very well thought out and engineered systems that exist on the market such as the EVO™ RIVETLESS™ and our FUSION™ DRILLFREE™ systems, which not only promote a zero exposed fastener look, but also greatly increase panel performance in real world scenarios. For example, the EVO™ system provides a 100% concealed fasteners look and the FUSION™ system, because of its patent serrated pocket design, makes the use of any screw being used during panel assembly, virtually impossible.

Both of these well thought out system designs ensure fabricators utilize proper manufacturing techniques during assembly. It is therefore almost impossible to supply a sub-par ACM panel product on a project when they are the preferred design and a competent manufacturer has been selected. Knowing that your chosen ACM panel design has been engineered and tested specifically to ensure the prevention of unfavorable assembly methods, means you’ve conducted your own due-diligence.

We hope that we have provided you with valuable information about how an ACM panel system can be properly assembled to ensure peak performance on every project, and this is of extreme value to the end user or your customer!

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