Metal Up Close: Insulated Panels

When it comes to insulated metal roofing panels, the value comes from the R.
For those installing insulated metal roofing panels, or foam core sandwich panels, or pre-insulated metal panels, they mostly are prescribed for R-value — a measure of the capacity of a material (usually some form of insulation) to impede heat flow. The insulation material may vary, but works well combined with a metal roofing panel.
“Traditionally, insulated metal roofing panels have been used extensively in temperature and humidity controlled environments, such as food processing and storage facilities,” says Paul Collyer, a sales and technical consultant with Metecno-API. “However, in recent years the largest use has been for commercial and industrial structures of all types. As energy costs have increased, people are searching for more energy efficient methods of construction, particularly as it relates to the roof, which for many low-rise buildings is the biggest source of heat gain and loss. Today we see insulated foam core roofing panels used in every market segment of construction, and particularly in the pre-engineered building sector, which encompasses a wide variety of end users.”
Bob Sterling of Centria says insulated metal roofing panels, like his company’s Versapanel, are best suited for straightforward applications where high R-values are desired, mainly for large industrial structures. Because it can be installed in larger sections, it can be a cost-effective installation. Sterling says the Versapanel is suited for applications where long spans are required. The concealed fasteners provide a clean uninterrupted surface. He says Versapanel combines the beauty of a metal roof, weatherproofing, insulation, and structural deck in a single, factory-built panel system.
Not every structure calls for an insulated panel, but there are a variety of practical applications. “In terms of insulation efficiency, the best possible place for building insulation is the exterior of the structural components,” Collyer says. “This allows the insulation to be continuous over structural elements without thermal shorts, and prevents condensation, which can develop in cavity based insulating systems. As insulated panels are rigid (non-compressible) and provide continuous foam-to-foam contact along each dimension of the panel, they provide maximum thermal effectiveness.”
Jay Smith of Metl-Span says insulated metal roof panels can be used in almost all applications like manufacturing facilities, industrial buildings, warehouses, multi-family housing, aircraft hangars, schools, athletic facilities, natatoriums, cooler facilities, food processing plants, and many others. “Any part of the country can and will benefit from the use of an insulated metal roof panel,” he says. “With the highest insulating value of all insulation products commercially available, this will lead to lower operation cost to any building owner.”
That’s an attractive selling point. Insulated panels are environmentally friendly, as the primary components (steel and foam) are composed of recycled content. Panels themselves can be recycled, and are often used in LEED certified projects.
“We see extensive use across all climactic conditions, literally from the North Pole to the South Pole and everywhere in between,” Collyer says. “People are looking for roofing systems that provide the best possible interior comfort level for the lowest energy expenditure. The greater the seasonal temperature variation in terms of heating/cooling degree days, the greater the need for high R-value roof systems. However, with current energy codes getting tighter all the time, such as the new California Energy Code Title 24, insulated panels are being used on a regular basis in even moderate temperature locations. The lifecycle cost benefits are significant, and as the old commercial used to say, ‘you can pay us now or pay the energy companies later.’”
Obviously, insulated metal roofing panels are delivered to jobsites ready for installation. The manufacturer takes care of all assembly and sizing of panels. Manufacturers contend installation isn’t all that difficult.
“For the most part they are installed the same way as a single skin metal roof, except that some sort of lifting equipment may be needed if long panel lengths are required,” Smith says. “Since an insulated metal roof panel is a structural panel, they can be used as working (walking) platform once they are installed. Metl-Span offers installation guides, videos, and can provide onsite technical assistance if required.”
Like the manufacturers of almost all metal roofing products, those manufacturing insulated panels are careful to ensure installers have the proper knowledge to do the job right. Collyer says Metecno-API is very thorough.
“Insulated panels are typically installed over light-gauge steel purlins or steel joists,” he says. “Spanning characteristics of the panels are available from the manufacturer, and take into account temperature differentials, wind loads, live and dead loads. Deflection characteristics are also calculated to make sure they comply with building codes. Manufacturers test their panels for compliance with wind uplift and fire testing to meet the standards of a Class A roof assembly. Recommended minimum slopes are typically 5:12.”
Collyer says it’s important to remember that although typical attachment methods of these systems provide a small amount of shear resistance, they should be treated from a design standpoint as a cladding system only and not as a shear panel. He says metal-faced foam core roofing panels are not the same as structural insulated panels, which do provide meaningful shear resistance. “Suitable cross bracing utilizing cables, strapping, rods, or angle iron within the roof framing should be relied upon to provide the necessary diaphragm action of the roof assembly,” Collyer says. “As compared to single skin metal roofing with batt insulation, foam core insulated panels themselves are no more difficult to install, but may require slightly more labor in handling the panels because being a composite, they are heavier.”
Collyer says the biggest savings come when R-factor requirements dictate the need for multiple layer roof/insulation systems, such as standing seam roofs with fiberglass over and between the purlins, separate vapor barriers, strapping, basket systems, thermal blocks, etc. “This is because foam panels are installed in one step,” he says. “Even though the material costs are slightly higher than the multi-component systems listed above, the in-place cost of foam panels is generally very competitive.”
That’s a selling point to contractors looking to take their business in another direction. A contractor capable of effectively installing insulated metal roofing systems can create a niche for himself in his market. And because insulated panels provide a variety of insulation and come in a variety of thicknesses, there are plenty of opportunities.
“Most all insulated metal roof manufacturers produce panels in thicknesses of two to six inches in one-inch increments,” Smith says. “Typically anything thicker than three-inch is used for refrigerated buildings such as food storage or food processing.”
Sterling worked closely with Centria’s project at Lincoln Financial Field in Philadelphia, home of the NFL’s Eagles. “For installations like at Lincoln Financial Field, it provides an attractive look, including a finished interior, and it’s capable of handling high wind loads, he says, adding the installation was made easier because sections were hoisted into place as a large piece. Versapanel double tongue-and-groove joinery, trapezoidal side seams, concealed clip system, and snap-on caps provide unsurpassed protection against moisture infiltration and leaks. Sterling estimates the choice of the Versapanel for the Lincoln Financial Field project saved approximately $3 a square foot — or almost quarter-million.
“Foam core roofing panels in the industry typically range from 1.5 inches to 6 inches, and are composed of a modified urethane foam core, also referred to as polyisocyanurate, which for purposes of this discussion can be considered the same,” Collyer says. “In moderate climates, 4-inch thick panels (R-33) provide more than enough insulation for commercial/industrial structures. Panels 5-6 inches thick are typically used only for cooler/freezer buildings or commercial/industrial projects located in extreme climate zones, like Alaska. It is also very important to note that the thermal efficiency of foam panels is maximized because the insulation is not compressed during installation, unlike fiberglass for instance. Sandwich panel R-values are often determined by in-place testing procedures, which result in true, installed R-factor roof assemblies.”
Collyer says while the overwhelming majority of insulated metal roofing panel applications are for cold storage and commercial/industrial applications, Metecno-API provides product for a handful of custom, higher-end large residences each year. “The biggest reason insulated metal panels are not used for residential construction is that the logistics of residential construction do not lend itself well to this product,” he says. “The typical house is relatively small, custom in nature, the contractor base is too large and the engineering and detailing coordination required for a successful installation is too complex.”

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