Insulated metal panels (IMPs) consist of a metal panel with a layer of insulation sandwiched between the two faces. These panels can be used for a variety of applications including walls, roofs and ceilings. There are a lot of advantages to using IMPs:
Different options for the liner of insulated metal panels meet different applications
Photos courtesy of ATAS International Inc.
- Energy efficiency: IMPs provide a barrier to heart transfer, which can reduce the amount of energy needed to heat or cool a building.
- Durability: The panels can withstand harsh, high-use conditions and are resistant to rot and fire, making them an ideal material to meet resilient building requirements.
- Ease of installation: IMPs provide the cladding, insulation, vapor barrier and interior finish in one building product.
- Low maintenance: They are easy to clean and resist corrosion and other weathering damage.
- Design flexibility: A variety of profiles, finishes, sizes and colors offer designers myriad options to create unique designs.
“The liner side of the panel provides a durable finished interior that can be cleaned or washed down when left exposed, which is very common on many commercial and industrial applications.”
RC Antal, insulation metal panel manager, ATAS International Inc.
When ordering an insulated metal panel, there are several options to choose from depending on specific needs and preferences. Perhaps most important is the core materials. IMPs are made with expanded polystyrene (EPS), polyurethane or mineral wool, and each material has different thermal insulation properties, fire ratings and costs. The type of insulation used depends on the specific application and performance requirements of the panel. Typical panels come in 8, 10 or 12 feet with a thickness from 2 to 6 inches. Most panels are 3 feet wide, but there are options ranging from 24 inches to 42 inches wide.
IMPs are manufactured using one of two methods. The foamed-in-place method involves injecting the foam core between the two metal facings. The panel is held in a mold while the foam cures. Foamed-in-place is the industry standard and fills all the voids while giving excellent panel adhesion. The second method is laminated. In this instance, the core is made prior to manufacturing and the metal facings are fastened with adhesives.
The resulting panel provides excellent thermal performance, structural strength, and durability, making it a popular choice for a wide range of building applications, including walls, roofs and ceilings.
“The standard color is usually referred to as ‘USDA White,’ which was in reference to a now-defunct specification produced by the United States Department of Agriculture.”
Bob Zabcik, PE, LEED AP, technical director, Metal Construction Association
Typical Liner
All those options are typical, and the back of the panel is also consistent. The innermost layer of the panel is the liner skin. It is designed to provide a smooth and durable surface for the interior of the building, while helping protect the insulation material from damage and moisture. It also helps to create a vapor barrier that can help to prevent condensation from forming on the interior surface of the panel.
The choice of liner skin material may depend on a variety of factors, including the specific application, the desired aesthetic appearance, and the level of durability required.
“The most common material is 26-gauge (0.06-inch) hot-dipped galvanized, or zinc-aluminum alloy coated steel, with a white polyester paint,” says Bob Zabcik, PE, LEED AP, technical director, Metal Construction Association. “It is also usually embossed, and the standard color is usually referred to as ‘USDA White,’ which was in reference to a now-defunct specification produced by the United States Department of Agriculture.” That coating is 1.0-mil white polyester that provides a durable, reflective and washable surface.
According to RC Antal, insulated metal panel manager at ATAS International Inc., Allentown, Pa., “The liner side of the panel provides a durable finished interior that can be cleaned or washed down when left exposed, which is very common on many commercial and industrial applications. The liner side of the panel has much greater aesthetics and durability when compared to traditional metal building system interiors, such as draped insulation.”
“The vast majority of manufacturers offer a very similar liner side type of panel, which doesn’t affect installation practices.”
Antal
Variations
Not all applications require the same liner panel, of course. “If acting as the interior finish, non-embossed stainless steel is often required in food processing areas for cleanability,” says Zabcik. “Embossing itself may not be allowed for sanitary areas or clean rooms either. Thicker gauges may be needed for puncture resistance in industrial settings. Also, partition panels may need heavier gauges to be able to span from floor to ceiling. In this case, they usually match since partition loads are considered to act in any direction.”
“A nontypical upgrade would be a higher quality finish, such as a Plastisol or PVDF [polyvinylidene fluoride] coating,” adds Antal. “Plastisol would be very common in applications that require high scrub-down requirements.
Scrub-down environments are a specific requirement in facilities doing food preparation, but “another nontypical backing would be unpainted stainless steel,” says Antal. “This would be used in chemical factories, cold storage or clean room environments.”
“Additional features such as non-white colors, thicker gauge, etc., all raise the price. Stainless is generally the most expensive option simply because of the high cost of the material itself. Embossing, however, is standard and does not raise the cost.”
Zabcik
Installation
One of great advantages of IMPs is their speed of installation. The three layers of the panel, in effect, replace three separate building materials or systems. The facer panel does the work of the substrate and cladding, the insulation layer replaces wall insulation, and the liner serves as the interior finish. The only thing the panel doesn’t provide in a building envelope is the structure, although panels do offer some structural benefits.
There are several installation methods for insulated metal panels including through-fastened, which involves attaching the panels directly to the building structure with the fasteners visible. This method is generally less expensive than other installation methods. Concealed fastener requires attaching the panels using clips or fasteners that are hidden. It provides a cleaner, more streamlined appearance but is generally more expensive.
On a typical job, such as a warehouse that isn’t very complex, a four-man crew can install up to 5,000 square feet during an eight-hour shift using 42-inch-wide panels. Narrower panels, such as 24-inch or 36-inch, reduce the square footage installed to about 20% of the area or 1,100 square feet.
There is little incentive to provide a liner panel that makes installation more difficult because it undermines one of the great advantages of IMPs. “Generally speaking,” says Antal, “the vast majority of manufacturers offer a very similar liner side type of panel, which doesn’t affect installation practices.”
There are exceptions, of course. “Some manufacturers will call for blind fasteners in the liner of an exterior panel when additional strength is needed to resist negative wind loads, i.e., loads acting to pull the panel away from framing,” explains Zabcik. “Some mineral wool core panels need supplemental stitch fastening on the fire side to obtain longer fire ratings. That could be the liner skin, fascia skin or both. Also, stitch fasteners in the liners may be called for to preserve in-plane stiffness, i.e., diaphragm, between adjacent panels when concealed fastening panels are used to span an opening in the wall.”
Cost
The number of factors affecting the cost of an IMP go well beyond just specifications for the liner. Among them are panel lengths and widths. Selecting multiple profiles will increase the cost, as will choosing multiple colors. Increasing the paint finish build from the typical 1.0 mil drives up the cost, and choosing higher-quality coatings such as PVDF or FEVE (fluoroethylene vinyl ether) adds to the investment.
For the liner, the standard liner is the least expensive option. “Additional features such as non-white colors, thicker gauge, etc., all raise the price,” notes Zabcik. “Stainless is generally the most expensive option simply because of the high cost of the material itself. Embossing, however, is standard and does not raise the cost.”
Antal points out that heavier gauge steel has an impact as well, and expands on the cost of stainless steel, noting that it will increase the price a lot, not just a little. Selecting 22-gauge instead of the standard 24-gauge will have an impact of course. “Nonstandard paint finishes, such as PVDF or Plastisol will also increase the cost,” he says.
Perhaps the most important thing to know about ordering an IMP and selecting options is that it’s crucial to work with a reputable manufacturer or supplier who can help you select the best options for your specific needs and provide you with high-quality panels that meet all relevant building codes and regulations.
