Metal Up Close: Through-fastened panels

Are you a metal roofing snob? Are you one of those guys who looks down his nose at through-fastened panels? Maybe your first metal experience was installing through-fastened metal roofing panels and you’ve since  “moved up” to the so-called architectural systems.
“I think we should not forget that although standing seam panels and stunning, flat, foam core, wall panel systems are all the rage today, it is the ribbed screw-down panel that has been the backbone of the metal building industry from its infancy through and including today’s modern structures,” says Dale Nelson of Roof Hugger, a manufacturer of sub-purlin system for retrofitting existing metal roofing systems. “It was the screw-down panel that made the pre-engineered industry possible. It is light, strong, durable and nests nicely together for easy shipping and handling. It is easily attached and works on roofs or walls. It has allowed the use of lighter primary framing and light gauge secondary framing and made large clear-span buildings possible. It has protected our troops and their equipment and given countless business an affordable facility from which to operate.”
Through-fastened metal panels are just what the name implies: metal panels that are fastened with screws or nails that go through the panel directly into a purlin or deck. They are used in new construction as well as for reroofing and retrofit applications.
In a message for homeowners on its website, the Metal Roofing Alliance offers the following on through-fastened panels: “In many cases, the exposed fastener is simply driven through an overlap in the panels’ courses as well as through other strategic locations as specified by the roofing manufacturer. Exposed fastener systems are usually lesser-quality systems and therefore are subject to lesser warranties than concealed fastener systems. The reason for this is that exposed fasteners are subject to the elements and tend to break down and fail much sooner than concealed-fastener panels. Exposed fasteners are normally self-drilling screws with a hex-head drive. These screws will typically have an oversized cap head that protects a neoprene washer that is in place for watertightness. The screws will normally be painted to match the roof system. Although the screws are self-drilling, most installers will pre-drill holes in the roofing from the backside to ensure proper placement.”
Through-fastened panels may have a reputation for being part of a lesser metal roofing system, but there is still a place in the world for through-fastened metal roofing panels and contractors are still finding a market for them.
For each profile, shape, and size, there is a reason to use through-fastened panels for a particular roofing project. No other profile is used for a wider variety of applications than the through-fastened panel.
Most agree installing through-fastened roofing panels doesn’t require the same level of expertise or craftsmanship as installing a standing seam panel. That’s OK. Through-fastened panels still boast all the benefits of metal — durability, attractive appearance, and weather resistance, to name a few — and are a solid offering for the able contractor.
There are several advantages for the installer as well as the customer for choosing through-fastened panels as opposed to standing seam panels. Most have to do with the bottom line.
“Through-fastened panels are normally chosen for economical reasons,” says Bill Croucher of Fabral. “They are more economical than standing seam panels and they are typically wider and install faster. Because no sliding details are required on these panels, they are simpler and faster to install. Additionally, these exposed fastener panels provide diaphragm action to stiffen the buildings. These panels also brace the purlins. Both of these items strengthen the building and reduce the amount of structural steel in the structure.”
Fabral’s Alu-Twin panel, for instance, is offered in widths of 40 and 48 inches. A handful of other profiles offer 36 inches of coverage. “Many of our through-fastened panels are used on many wood framed structures,” Croucher says. “This includes agricultural buildings, some light commercial, and some residential. They are also used on some pre-engineered buildings.”
Most manufacturers offer through-fastened panels, ranging from 5-v crimp and corrugated to R-panels and rib panels. Homeowners in Florida have fallen in love with 5-v crimp roofing, popular on the Cracker style houses with large porches. They have to have the look of the 5-v crimp — which includes the straight lines of fasteners — and appreciate the fact it is less expensive than concealed fastener systems. Most panels are 26 inches wide (manufactured from 27-inch coil) and provide 24 inches of coverage with a 1-inch overlap on each side. A panel that takes less time to install will cost less.
“Through-fastened panels do have advantages other than economic reasons,” Croucher says. “They can be designed as deeper, stronger panels so they can span further than standing seams. Standing seam panels usually do not span further than 5 feet and, depending on the wind loads, the spans may have to be much shorter. Exposed fastened systems can span as far as 15 or more feet by using deep profile panels.”
It’s apparent that through-fastened systems may be more appropriate for large commercial or industrial applications than standing seam roofing or other concealed fastener systems.
Today’s through-fastened systems are better than the galvanized panels used in the early days of the metal building industry, but many of those 40-50-year old buildings are holding up admirably today. Nelson says some of these buildings are in need of new roofs, which are subject to much more exposure to the elements than the wall panels. That’s where the Roof Hugger comes in.
“Of course everyone hates to put on a new roof but even that is not hard or super expensive and if you think about the initial cost, the years and years of service with little or no maintenance in a wide variety of climates and hostile environments this simple screw-down metal panel has endured, I think you would agree it is truly an amazing product,” he says. “It’s a product which more than one of us owes our livelihood to.”
There you have it. The through-fastened metal roofing systems are the pioneers of today’s architectural panel systems. Technology and innovation provided today’s installers, homeowners, building owners, architects, and specifiers with a wider variety of products for a wider variety of applications. Without a doubt, there are better systems in many applications, but there is still a market for through-fastened panels.

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