The huge printing press of a major newspaper began malfunctioning on the Saturday before Christmas, putting the revenue for holiday advertising in jeopardy. None of the technicians could track down the problem. Finally, a frantic call was made to the retired printer who had worked with the press for 40 years. “We’ll pay anything; just come in and fix them,” he was told. He arrived and surveyed the press, approaching one of the control panels. He removed a dime from his pocket, turned a screw one-quarter of a turn, and left. His bill arrived a few days later for $10,000! The newspaper did not want to pay such a large amount for so little work, so the printer was told to itemize his charges. The revised bill arrived: $1 for turning the screw and $9,999 for knowing which screw to turn.
Morale of the story? Expertise has a cost, and the lack of industry know-how can be crippling. American psychologist Abraham Maslow once wrote, “If your only tool is a hammer, every problem looks like a nail.”
A quick survey of screw types revealed more than 50 distinct types with 20-plus internal drives and another dozen external drive types. This article will not exhaust the entire variety of screws, let alone the sheer volume of the broader category of fasteners. Instead, it will delve into the fascinating world of climate-controlled environments and what holds those big, beautiful, insulated metal panels (IMPs) together.
The story behind IMPs
For the uninitiated, modern IMPs consist of two layers of 24-gauge Kynar-coated metal skins with various thicknesses, usually 50 to 203 mm (2 to 8 in.), of rigid insulation between them.
First developed in the 1930s by President Franklin Delano Roosevelt and the U.S. Forest Service, structural insulated panels offered a process with greater insulation properties and that conserved forest resources. In 1950, Alden Dow, son of the founder of Dow Chemical, innovated the next generation of panel technology, introducing polystyrene foam as the insulation method. By the 70s, these panels became the prevalent building material in North America and Europe. Over the last decade, IMPs have shown annual double-digit sales growth.
IMPs create a protective barrier against water, air, vapor, heat, and cold, and deliver high energy efficiency. These attributes make them ideal for cold-storage facilities, aircraft hangars, and manufacturing plants. Data centers are a perfect opportunity for IMPs since precise climate control protects sensitive equipment. Thermally broken fasteners help maintain energy efficiency in server rooms, while corrosion-resistant fasteners ensure durability in humid cooling environments. Other growing applications, such as pharmaceutical, semiconductor, and biotechnology cleanrooms, are also benefiting from IMPs.
Proper installation is essential
IMPs are designed for efficient installation, and according to the Metal Construction Association, a trained crew of four can erect as many as 465 m2 (5,000 sf) of the material in an eight-hour shift. Incredibly efficient in their design, IMPs must be properly installed to maintain their benefits, placing unique demands on fastening systems.
Contractors utilize a variety of installation methods, which require a variety of fasteners. Self-drilling fasteners became widely available in the 1960s and are popular for their installation speed, versatility, and ease of use. They are primarily used to secure the IMP to structural frameworks in walls, roofs, and ceilings either directly through the panel or through attachment clips. Aircraft hangars and other high-vibration environments are ideal applications for Fabloks and Bulb-Tite rivets. These are often used in conjunction with butyl tapes and sealants to create waterproof joints.
Self-drilling fasteners come in a variety of head styles, diameters, drill points, and metal compositions. Self-drillers are commonly made from different grades of carbon steel, although stainless steel in 300 and 410 grades is also common. Bi-metals (featuring a carbon steel drill point and starter threads with a 300-series stainless shank and head) are becoming more popular, particularly in more corrosive environments such as coastal areas or buildings that require frequent washdowns.
Contractors can find a large inventory of carbon steel self-drillers with the industry standard 1000-hour salt spray long life coating in variety of diameters from #6 to 5/16” and lengths from 0.38 to 12 in. Head styles range from hex washer heads (HWH), truss heads, pancake (clipfast) heads, and flat undercut.
How is the proper fastener chosen?
One of the most important factors to consider is what material the IMP is being fastened to. If it is metal to metal, a self-drilling screw is the choice. Material thickness and the fastener’s termination determine what drill point is needed.
Drill point types
- #1 drill point is for light-gauge materials (.018–.060), such as steel or aluminum skins. The point ensures precise penetration and good extrusion, allowing maximum pullout values, even in thin material. It is ideal for attaching to lightweight framing.
- #2 drill point is for slightly thicker material (0.36-0.125). The longer drill point allows for more extruded material to be fastened into.
- #3 drill point is for medium-gauge steel (.060–0.250); this point offers a balance of speed and strength. It is commonly used in industrial IMP applications, such as warehouse walls and roofs, where moderate structural loads are present.
- #4 drill point is for attachment to
heavy-gauge steel (0.125–0.250) and is robust and capable of penetrating thicker substrates. It is used in cold storage facilities where IMPs are secured to heavy steel frameworks. - #5 drill point is for extra-heavy-gauge materials (up to 0.500), including structural steel beams. It is critical for high-load applications, such as
large-scale refrigerated warehouses or data center enclosures.
Determine the required length and diameter
The length and diameter of the screw are critical factors to consider. The length of the screw should be long enough to go through both materials being fastened (excluding the drill point) and provide full thread engagement, without causing unsightly protrusions. The diameter is usually determined by the strength characteristics required.
- #8 is used in flashing applications. It primarily comes in a Phillips Wafer (also known as K-Lathe) head, and due to its low profile, it is virtually undetectable.
- #10 is used for light-duty applications, such as attaching to thin metal framing in cleanrooms or architectural facades.
- #12 is the most common IMP installation. It offers a balance of strength and ease of installation and is widely used in cold storage and commercial buildings and is available with #3 and #5 drill points.
- 1/4” is a larger diameter fastener for heavy-duty applications, such as securing IMPs to thick steel girders in industrial facilities. It comes with #3 or #5 drill points for maximum penetration and holding power. Thread configuration can be 1/4—14, 1/4–20, or 1/4—28, depending on the materials needing to be fastened.
- 5/16” is used in specialized, high-load scenarios, such as
seismic-rated structures or extreme wind zones. This diameter ensures exceptional shear and tensile strength, critical for large climate-controlled environments.
Consider the type of head
Screw heads come in different types, such as flat, hex washer, pan, pancake, and round. The type of head chosen will depend on the specific application. Hex washer heads are used in panel fasteners where the panel clip attaches the panel to the structure. These heads can also be found where the trim attaches to the panel skin. Flat heads are used when a low profile is needed due to another piece of metal, such as trim being placed over a panel. Low-profile pancake fasteners are ideal for maintaining sterile conditions and preventing particle contamination due to a limited surface area where contaminants can form. The use of a low-profile pancake head eliminates any interference in the mating of panels.
Check the thread pitch
An overlooked aspect of fastener selection is the thread pitch, which refers to the distance between the threads on the screw. Choosing the right one is important for ensuring the most secure hold. A fine thread pitch is suitable for harder materials such as structural metal, while a coarser thread would be better for mild steel.
Corrosion-resistant coatings
Perhaps the most important aspect of fastener choice is corrosion resistance. Zinc or hot-dipped galvanizing used to be the industry standard. However, more customers are demanding long-life coatings that offer 500-hour, 1000-hour, or higher salt spray ratings. If the project is exposed to the harsh elements or a high-moisture environment, it is important to choose screws that are 300-series stainless steel or even 316 stainless for the most corrosive environments, whether marine or chemical. Some of these also offer an additional long-life coating.
Do not forget about aesthetics
While the functionality of the screw is important, installers also need to consider its appearance. Fasteners should be the invisible glue that holds things together.
Pancake, truss, or countersunk flat head fasteners are recommended head styles that provide a seamless look. They are typically used in concealed fastening systems, where the fastener is hidden beneath overlapping panel joints to maintain a clean appearance and enhance weather resistance. Additionally, they can be used to fasten in architectural facades. Meanwhile, hex washer heads provide a more industrial look.
Thermally broken fasteners
Thermally broken fasteners incorporate non-conductive material, such as nylon, rubber, or plastic, between the metal components to reduce thermal conductivity. These fasteners are critical in climate-controlled environments, such as freezer rooms or data centers, where maintaining consistent internal temperatures is essential.
Gasketed fasteners
Gasketed fasteners feature an ethylene propylene diene monomer (EPDM) or Neoprene washer that compresses during installation to create a watertight and airtight seal. Though usually available in a separately assembled bonded washer, FSI also features a line that has an encapsulated EPDM rubber washer that fits securely inside a hex flange head for an attractive finish.
Conclusion
Winston Churchill appealed to the United States, “Give us the tools, and we will finish the job.” While Churchill was referring to winning the Second World War, the same principle applies.
Specialized fasteners are indispensable in the insulated metal panel and climate-controlled environment industries, ensuring structural integrity, thermal efficiency, and environmental resistance. By selecting the appropriate fastener, builders can optimize performance in cold storage, cleanrooms, data centers, and commercial buildings. As technology advances, innovations in fastener design will continue to enhance the durability and sustainability of these critical systems.
Wade Douglas is the senior purchasing manager for Fastener Systems, Inc. He has more than 27 years of experience in procuring and developing specialized fasteners, sealants, and other accessories for the climate-controlled environment industry.
