Insulated metal panels
(IMPs) act as an all-in-one water, air, vapor and thermal barrier. By containing an advanced urethane core that provides efficient insulation properties, IMPs provide building owners with an energy-efficient building envelope with lower heating and cooling costs.
IMPs are also lightweight and are available in a range of colors and finishes. Common applications include large commercial and industrial facilities, such as cold storage facilities, hangars, manufacturing plans, food-processing facilities, office buildings and convention centers.
By providing a single-source for the building enclosure, IMPs are designed for easy and efficient installation by reducing the number of required trades and by keeping projects on track. “IMPs install quickly and efficiently with buildings dried-in to allow interior work to begin,” says Kim Harrell, national sales manager at All Weather Insulated Panels (AWIP), Vacaville, Calif. “The air and water barrier is installed in one step in almost any weather condition.”
One-Step Process
When installing IMPs, it is important to use qualified and experienced installers. According to the Lewisville, Texas-based Metl-Span‘s Installation Guide, the installer should always review and understand the project’s installation drawings and any installation guide prior to installation, and panels should always be installed in accordance with the project’s installation drawings.
Depending on the job complexity and size, the Metal Construction Association‘s “Selection Guide for Insulated Metal Panels,” notes IMPs can be erected at a rate of up to 5,000 square feet per eight-hour shift by a four-man crew on an industrial project, and up to 1,100 square feet per eight-hour shift by a four-man crew on an architectural project.
When compared to other materials, the MCA Selection Guide says IMPs minimize the erector impact on the system performance, resulting in better in-place quality, weather integrity and appearance.
IMPs are generally bundled according to length, so Harrell recommends contractors should inventory, store and stage panels to make installation more efficient. “IMPs should be stored and handled according to the manufacturer’s instructions to limit the possibility of job-site damage,” he says.
Structural Framing
To prevent structural and aesthetic issues with the finished product, framing needs to be within the IMP manufacturers’ design criteria. “Metal building girts are often blocked into place to ensure girts are level until the IMPs are installed, at which point the blocking can be removed,” Harrell explains.
Because factory insulated metal panels are strong and rigid, the MCA Selection Guide says the structure they attach to must be held to a closer tolerance than that required for some other systems. Excessive variation from the theoretical plane can subject IMPs to undo stress, resulting in aesthetic changes or diminished load capacity. Additionally, it says the alignment of supports is especially important with the most commonly used back seal or liner-side seal systems where the support alignment establishes the final alignment of the wall.
The Metl-Span Installation Guide also notes that the structural framing should be properly designed to accept the erection and design loads as imposed by the wall panels. And, the location of the interior and/or exterior panel joint and perimeter seals should be properly specified for the project’s moisture an vapor control requirements.
Structural and panel shop drawings should be compared to ensure the wall supports are in the correct location. Any variations must be corrected prior to starting installation.
Cutting Panels
To cut IMPs, installers should always wear safety glasses, gloves and long-sleeved shirts. The Metl-Span Installation Guide recommends using either a circular saw with carbide-tipped, metal-cutting blade, an insulated metal panel saw or a band saw with metal-cutting blade.
“Installers should never use a reciprocating blade to cut IMPs or delamination can occur,” Harrell explains. “Screw guns with adjustable torque are used to quickly install self-drilling fasteners, while ensuring fasteners are not over-torqued.”
For smaller penetrations, the Metl-Span Installation Guide says the panel face can be cut with a portable router, while the foam should be cut with a serrated knife. Metal flashings can be cut with power snips, nibblers or hand snips.
To prevent surface rust, Harrell adds that field-cut IMPs should have all metal shavings removed. And, to prevent collection of dirt over the lifetime of the building, any exposed sealants should be cleaned per manufacturer’s recommendations.
Panel Caulking and Sealants
Before lifting the IMP panels into place, Harrell says wall panel sealants should be applied in the panel joints in the field. “Sealants are non-exposed, non-skinning butyl contained within the wall and roof panel joint,” he adds.
To achieve the noted air and water infiltration performance levels, a proper seal system is imperative. The MCA Selection Guide explains a common technique is the liner side seal network, which involves field applying non-skinning butyl sealant on the structural steel at panel ends and connecting them to either shop- or field-applied sealant located in the panel side joint. This results with each panel having a complete perimeter of butyl sealant on the liner side, which creates an excellent vapor barrier. At transition areas, such as corners or wall-to-soffit edges, proper liner trim is needed to maintain the liner seal continuity.
If the panels come with factory-applied sealant, the Metl-Span Installation Guide recommends contractors inspect the panels for consistent bead size and add any sealant as required.
Lifting and Installing Panels
Panels are lifted into place with suction lifting equipment or other industry standard methods. “When standing longer IMP’s without a suction lifter, IMPs are turned on edge and then lifted from the bundles to eliminate over-flexing the IMPs and potentially causing damage,” Harrell explains.
According to the AWIP Insulated Wall Panels General Installation Guide, the bottom end of the panel should be placed on the base and the panel tilted into position. The panel should be slid into the groove of the preceding panel using firm, gradual pressure to draw panels together. Panels should not be pound into place. To ensure a consistent joint modulation, AWIP suggests using plastic spacers at the exterior side as the panels are being engaged. Be sure each panel is plumb and square before installing fasteners.
Fasteners
Harrell says IMPs are generally installed with concealed clips and self-tapping Tek-style fasteners. Depending on the end application and architect’s expectations, he says to use pop-rivets of self-tapping Tek-style fasteners to install trim.
To achieve the published load values, the MCA Selection Guide advocates using fasteners and clips as recommended by the panel manufacturer. Both should be installed in accordance with the manufacturer’s instructions, as verified by the structural calculations. Make sure not to overdrive or underdrive the fasteners, as it could result in leakage.
According to the Metl-Span Installation Guide, suggested fastener driving speeds are 1,800 rpm for carbon, zinc plated and 410 stainless steel fasteners, and 1,000 rpm for 304 stainless steel fasteners.
Cleaning Panels
After installation, panel surfaces should be wiped with a wet, soft cloth to maximize the performance of the coatings while removing all dirt, oil, grease or other contaminants. To remove superficial oxidation and tough stains, AWIP recommends using a regular household cleaner followed by a thorough rinsing. If touch-up paint is required, contract the panel manufacturer to obtain touch-up paint or a paint chip for color matching.
