Standard Testing For Metal Roofing – Part 2: Air and Water Resistance

In a prior post, we discussed the importance of independent (i.e. third party) standardized testing as a means of verifying the performance of metal roofing, and specifically looked at structural and wind uplift performance. In this post, we will similarly look at testing standards but focus on metal roofing tested for air leakage and water penetration.

Air Leakage and ASTM E1680

Keeping air from passing through a building system from the exterior to the interior (i.e. drafts) is a fundamental role of any building envelope system, including roofing. It is also important in controlling the flow of harmful airborne moisture into a roof assembly. Hence, testing a roofing panel for its ability to control air leakage is critical to the long-term success of the roofing system, and ultimately, the building.

ASTM E1680 “Standard Test Method for Rate of Air Leakage Through Exterior Metal Roof Panel Systems” is used to determine “the resistance of exterior metal roof panel systems to air infiltration resulting from either positive or negative air pressure differences”. It is a standard procedure for “determining air leakage characteristics under specified air pressure differences”. The test is applicable to the field portion of any roof area including panel side laps and structural connections but not at openings, the roof perimeter, or any other details. The test is also based on constant temperature and humidity conditions across the roofing specimen being tested to eliminate any variation due to those influences.

The standard test procedure consists of “sealing and fixing a test specimen into or against one face of an air chamber, supplying air to or exhausting air from the chamber at the rate required to maintain the specified test pressure difference across the specimen, and measuring the resultant air flow through the specimen”. Basically, the test is meant to reveal the ability of the selected roofing panel to resist the difference in air pressure between the two sides and thus demonstrate its air tightness.

The beauty of this standardized test is that different metal roofing products can be tested under the same conditions and compared. The standard calls for a pressure differential between the two sides of positive and negative 1.57 foot pounds of pressure per square foot of panel (75 paschals of pressure) and can be tested in the negative pressure mode alone if the roof slope is less than 30 degrees from horizontal.

MBCI's metal roofing products are tested to confirm airtightness and water permeability.
MBCI’s metal roofing products are tested to confirm an air tight and water-resistant roof.

Water Penetration and ASTM E1646

In addition to air leakage, water leakage in roofing systems is obviously not desired. To test the performance of metal roofing products in this regard, ASTM E1646 titled “Standard Test Method for Water Penetration of Exterior Metal Roof Panel Systems by Uniform Static Air Pressure Difference” is the norm. This standard laboratory test is not based solely on free running water, but on water “applied to the outdoor face simultaneously with a static air pressure at the outdoor face higher than the pressure at the indoor face, that is, positive pressure”. This pressurized testing is intended to simulate wind-driven rain and flowing water that can build a head as it drains. The test measures the water-resisting properties of the roofing in the field of the roof panels including panel side laps and structural connections. Just like air testing, it does not include leakage at openings, perimeters, or other roofing detail areas.

The test method itself consists of “sealing and fixing the test specimen into or against one face of a test chamber, supplying air to or exhausting air from the chamber at the rate required to maintain the test pressure difference across the specimen, while spraying water onto the outdoor face of the specimen at the required rate and observing any water leakage”. Hence, it requires the air and water to be supplied simultaneously and for the testers to observe and document the rate of water leakage under the test conditions.

The test parameters typically require at least 20 gallons of water per hour (gal/hr) overall with between 4 – 10 gal/hr in any quarter section of the tested specimen, all at specified air pressure differentials. Given that this is a fairly stringent test, it is fair to say that metal roofing that holds up under these test conditions will likely perform well under most weather conditions when installed on a building. Typically, manufacturers have developed metal roofing products with seaming and connection methods that allow them to pass this test with virtually no observable water penetration.

To find out more about the tested results of metal roofing products you may be considering, contact your local MBCI representative or see the MBCI website and select the “testing” tab under a selected product.

Standard Testing for Metal Roofing – Part 1: Structural Performance and Uplift Resistance

When selecting a metal roofing product, there is an expectation that it will perform as intended over the life of the building. But what assures building owners, code officials, or design professionals that a product will in fact perform as promised? This question often comes up in building product discussions and the accepted way to answer it is to subject the products to physical testing. The type of testing is usually very specific to the product based on protocols and procedures developed by independent agencies such as Underwriters Laboratories (UL), ASTM International, or others. Manufacturers typically submit their products to independent testing labs who follow these standard test procedures. Once testing has concluded, they report the results back to the manufacturer. These results then show whether the product meets stated performance criteria or not. If not, the manufacturer can re-design and re-test until it does and then make the final results available to the public.

For metal roofing, a series of relevant and important tests are typically performed. In this blog, we will look at two of them related to structural performance and wind uplift.

ASTM E1592

The structural integrity of metal roofing is crucial given the various natural forces that can be imposed on the materials. Effects from wind, snow, or other conditions can compromise its integrity. Accordingly, the ASTM Committee E06 on Performance of Buildings (including sub-committee E06.57 on Performance of Metal Roof Systems) has developed ASTM E1592 “Standard Test Method for Structural Performance of Sheet Metal Roof and Siding Systems by Uniform Static Air Pressure Difference”. While the standard acknowledges the use of computation (i.e. calculations) to determine the basic structural capacity of most metal products, it also points out that some conditions are outside of the scope of computational analysis and hence need to be tested.

The standard describes a test method with “optional apparatus and procedures for use in evaluating the structural performance of a given (metal) system for a range of support spacings or for confirming the structural performance of a specific installation”. As such, it is very specific both to metal roofing and its installation. This test method uses imposed air pressure not to look at air leakage but simply to determine structural reactions. It consists of three steps:

1. Sealing the test specimen into or against one face of a test chamber

2. Supplying air to, or exhausting air from, the chamber at the rate required to maintain the test pressure difference across the specimen

3. Observing, measuring, and recording the deflection, deformations, and nature of any failures of principal or critical elements of the panel profile or members of the anchor system

The test needs to be performed with enough variation to produce a load deformation curve of the metal and account for typical edge restraint (fastening) representative of field conditions.

Manufacturers need to submit different products that are tested at least once at two different span lengths between supports. Standing seam roof panels are typically tested at a 5’-0” and 1’-0” span. Spans between the two tested spans can be interpolated. The result is a table of tested loading results that can be compared to code required or engineered design loading to then determine if the selected material and spacing are adequate for the project needs or if another product or spacing is needed.

MBCI's metal roofing products undergo a series of tests to ensure maximum resistance and performance.
MBCI’s metal roofing products undergo a series of tests to ensure maximum resistance and performance.

UL 580

The ASTM E1592 test is focused on the structural integrity of metal panels. It also uses positive and negative air pressure in a static (i.e. non-moving) condition to determine performance. There is also a separate concern about how metal roofing will perform in a dynamic condition as would be expected in a windy condition where wind gusts can ebb and flow erratically. In that regard, a separate test developed jointly between Underwriters Laboratories (UL) and the American National Standards Institute (ANSI) looks at the ability of roofing to resist being blown off a building due to wind. Known as ANSI/UL 580 “Standard for Tests for Uplift Resistance of Roof Assemblies”, it has become the recognized means to identify and classify the suitability of roofing for different wind conditions – low to high.

This test is also specific in its scope and intent stating that it “evaluates the roof deck, its attachment to supports, and roof covering materials”. It also points out that it is not intended to test special roof conditions, main or secondary structural supports, or deterioration of roofing. The standard prescribes in considerable detail the type of test chamber that needs to be constructed and used for the testing which includes three sections: “a top section to create a uniform vacuum, a center section in which the roof assembly (i.e. deck, attachment, and roofing) is constructed, and a bottom section to create uniform positive pressure”. The test procedure is then based on placing the roof assembly into the test chamber and subjecting it to a prescribed sequence of 5 phases of oscillating positive and negative pressure cycles (simulating dynamic wind conditions) over 80 minutes of total testing.

There are four wind uplift classifications obtainable for a tested assembly based on the test assembly retaining its attachment, integrity and without any permanent damage. These include Class 15, Class 30, Class 60, and Class 90. Each class has its own requirements for test pressures with increasing pressure as the class number increases. Higher class numbers indicate increasing levels of wind uplift resistance. Note, that to obtain a Class 60 rating, the tested assembly must pass the Class 30 test then be immediately subjected to the Class 60 test sequence. Similarly, to obtain a Class 90 rating, the tested assembly must first pass both the Class 30 and 60 tests. Metal roofing manufacturers who want their roofing products tested and classified under UL 580 must pair them with standard roof deck and fastening materials. Hence most have many different tests performed and results reported accordingly.

When reviewing metal roofing options, it is comforting to know that most manufacturers have tested their products and designed them to meet or exceed minimum requirements. To find out more about tested results of products you may be considering, contact your local MBCI representative or see the MBCI website and select the “testing” tab under a selected product.

Sealing the Deal: The Importance of Properly Sealing the Building Envelope Using IMPs and Single-Skin Panels

The primary purpose of a building’s envelope (roof and walls) is to protect the building’s interior spaces from the exterior environment and provide the desired exterior aesthetics. Whether choosing insulated metal panels (IMPs) for their superior performance or, instead, looking to the wide range of aesthetic choices available with single-skin panels—or some combination of the two—the common goal must always be to protect the building from the potential ravages of water, air, vapor, and thermal/heat. By ensuring proper installation of metal panels and, thereby, properly sealing the building envelope, problems can be mitigated, efficiencies maximized, and the integrity of the building protected.

Here, we’ll briefly consider the benefits of each panel, and some key considerations relative to their sealant needs and capabilities.

Insulated Metal Panels (IMPs)

IMPs are lightweight, composite exterior wall and roof panels that have metal skins and an insulating foam core. They have superior insulating properties, excellent spanning capabilities, and shorter installation time and cost savings due to the all-in-one insulation and cladding. In effect, IMPs serve as an all-in-one air and water barrier, and are an excellent option for retrofits and new construction. With their continuous insulation, roof and wall IMPs provide performance and durability, as well as many aesthetic benefits.

IMPs offer excellent R-value and improve energy efficiency to the building envelope.
IMPs offer excellent R-value and improve energy efficiency to the building envelope.

Generally speaking, because of the nature of the joinery, it is easier to get a good seal in place with IMPs given their relative simplicity (i.e., putting the two pieces together with the sealant). They require great attention, though, in terms of air and vapor sealing—aspects largely controlled by the installers on a given project. As an example, vapor sealing in cold climates or applications is critical to the overall soundness of a building. Consider the damage a building could incur if moisture seeps into a panel and becomes trapped; it if freezes, it could push panels out of alignment. This would result in not just an unattractive aesthetic, but a performance failure as well. In order to be effective, all sealant and caulking must be fully continuous.

Single-Skin Panels

Single-skin panels, alternatively, offer the advantage of an expansive array of colors, textures and profiles. They are also thought to have more “sophisticated” aesthetics than IMPs. Single-skin panels are available in both concealed fastener and exposed fastener varieties, and are part of an assembly. They can be used alone or in combination with IMPs, and as long as the needed insulation is incorporated, single-skin panels can meet technical and code requirements, depending on the application. Single-skin products offer a wide range of metal roof systems and wall systems as well.

Getting the proper seal on single-skin panels may require extra sealants or closures, and have more parts and pieces that have to come together to create the seal. However, when properly installed and sealed, they can provide excellent performance in their own right. Some key caveats include ensuring panel laps are properly sealed with either tape or gun butyl sealants, and carefully inspecting air and water barriers for proper installation as well as penetrations through the wall for sealing/fire caulking prior to panel.

In most cases, following the details for the most common conditions will give you a successful and high-performing outcome.

Regardless of the type of metal panel used, taking the time and effort to ensure the sealing and caulking details are properly handled, metal buildings can protect the built environment and provide long-lasting quality and performance.

Level of Development (LOD) BIM Specifications for Metal Buildings

When designing and constructing metal buildings, an increasing number of professionals are using a computerized building information model (BIM) as their primary tool. This allows for detailed, three-dimensional computer models to be created, not only to develop the design, but to identify material lists, coordinate details, avoid conflicts between building systems and streamline the design and construction process.

Problem: BIM Coordination

Of course, design is a process that requires some back-and-forth between multiple parties to arrive at the best final solution. So, when a metal-building supplier or manufacturer is asked to provide their information to be incorporated into a BIM process, the question that naturally comes up involves the level of detail. This is common across all trades, and fortunately, there is an organization that is addressing this issue. Known as the BIMforum (www.BIMForum.org), is is the not-for-profit United States chapter of buildingSMART International, and its mission focuses on improving BIM technology, collaboration, education, innovation and open information exchange. As they describe themselves, “Co-sponsored by the Associated General Contractors of America (AGC) and the American Institute of Architects (AIA), BIMForum seeks to lead by example and synchronize with counterparts in all sectors of the industry to jointly develop best practice for virtual design and construction.”

Solution: Level of Development (LOD) Specification

A flagship publication of BIMForum is the 2016 version of Level of Development (LOD) Specification. Having evolved over several years, this publication is “a reference that enables practitioners in the AEC Industry to specify and articulate with a high level of clarity the content and reliability of Building Information Models (BIMs) at various stages in the design and construction process.” Coordinated with other industry standards, it “defines and  illustrates characteristics of model elements of different building systems at different Levels of Development.”

Essentially, it defines and standardizes how much detail is expected in a building information model at different stages of design development. Therefore, if a metal-building manufacturer or any other trade is asked to supply its BIM information, then it needs to ask “What Level of Development?” so that is it providing the right amount of information to coordinate with the larger computer model for the building.

How LOD Works:

The LOD Specification is based first on the familiar Uniformat specification sections used by most spec writers. Metal Buildings commonly fall under Special Construction in Section F1020.40 in the Uniformat approach, or 21-06 10 20 40 in the Omniclass approach, and are found that way in the LOD Spec. From there, five levels of detailing are described by the numbers 100, 200, 300, 350 and 400, as described further below.

  • LOD 100 – This is the most basic of model, described as “Generic mass of special structure with system typically noted with a design narrative for conceptual pricing.” It is likely that this level of BIM is already developed by an architect or engineer and given to a manufacturer or supplier as a starting point.
  • LOD 200 – This level calls for basic primary structural member sizing, generic representation of secondary framing, and general cladding and exterior trim to be provided, including openings.
  • LOD 300 – More-specific sizing of all needed primary frame structural members, web tapers, frame connections and similar details are called for at this level. Similarly, secondary framing needs to be shown, including purlins and bridging, girts, subframes and base conditions. Exterior panel and trim with actual profiles, actual openings and all significant trim and accessories are shown here.
  • LOD 350 – This level starts to show coordination with other elements or building systems. Therefore, for the primary structure, things like base plate locations, bracing/gussets, clips and any reinforcement all need to be included. Secondary framing elements need to include similar details, such as nested members, connections to primary structure, any miscellaneous or secondary steel members, bridging, etc. Cladding and exterior trim would include all actual profiles, closures, downspouts and all minor trims shows at least generically.
  • LOD 400 – This is the full-fabrication level equivalent to shop-drawing level of detail. As such it includes all final details, including welds, bolts, holes, cinching and all other details of fabrication and assembly for primary and secondary framing, plus all cladding and trim.
BIM
Level of Development (LOD) Specification Example – image courtesy of BIMForum.org

By using these standardized Levels of Development, all design and construction professionals can proceed in an orderly sequence to provide the appropriate information, receive coordination feedback and then move on accordingly to the next level.

The full 2016 LOD Specification can be downloaded for free at http://bimforum.org/log/. The specific information for Metal Building Systems can be found on pages 177–186. For information on how to work with a manufacturer to provide the appropriate BIM information, contact your local MBCI representative.

Knowing When to Call the Metal Manufacturer: Part 2

As stated in Part 1 of this series, the success of a metal roof or metal wall project can rest on the installer knowing when something isn’t working or just doesn’t seem right. When that happens, a call to the manufacturer is not just suggested but is really imperative to ensure any potential problem is averted before it’s too late. In addition to the previously discussed scenarios, such as damage to the physical panel or problems with the fasteners, let’s take a closer look at a few other common circumstances under which MBCI recommends immediately reaching out to the manufacturer:

Alignment and Substrate Issues

It is the installer’s responsibility to verify the substrate and check for proper alignment before attaching any sheeting materials. If the installer notices any issues of this sort (either before installation or once they start putting on the sheeting), they should stop and address them immediately. This might include oil canning or other irregularity in the appearance of the panel. The installer should investigate the source. If unable to identify and properly remedy the situation on their own, then a call to the manufacturer’s support team is recommended. They may be able to suggest items to check to help locate the source of the problem—whether it be installation or manufacturing—and from there make suggestions as to the best possible means to address the situation.

Accessories

When physically getting ready to modify a panel system by adding things to the roof (such as snow guards or mechanical curbs) or to walls by installing doors, windows and louvers, these penetrations can have an impact on the system and its weather-tightness and appearance. Oftentimes, other trades—who may or may not have knowledge of the sheeting system—are coming onto the job to perform the accessory installation. It’s wise to visit with manufacturer prior to installation and/or alert the non-metal panel installer of precautions to take when adding accessories.

bad roof jack installation - part #2 ACCESSORIES SECTION
The pipe penetration shown here is not the correct type of piping for metal roofing, and not the correct installation. This can lead to issues with roof performance, including leaking and water damage.

Coordination regarding material types of accessories, fasteners and placement is critical. There are materials that can react negatively with the installed system and lead to damage as well as void manufacturers warranties. Accessories should always be discussed prior to installation. Read more about different types of roof accessories and penetrations in MBCI’s blog article, Roof Penetrations Made By Non-Roofing Contractors.

Panel Engagement

Panel systems have an engineered means by which the panels attach and engage one another as shown in the manufacturer’s installation manuals and project drawings. If at any point the panel will not engage as depicted in the details, installation should be halted and reviewed to determine the cause. This can require a call to the manufacturer to help determine if the matter is site and substrate related or potentially a manufacturing issue.

Do not continue to install the system if the laps are not nesting properly, clips are not engaging as detailed, panel modularity cannot be controlled or if the overall panel is not “resting” on the substrate such that there is excessive bowing and stress in the panel. This is the time to call the manufacturer, as once the material is completely installed, it is much more difficult to determine the cause of a problem and is potentially more expensive to remedy. Additionally, in many cases, full installation constitutes acceptance of the product and the manufacturer’s hands could be tied or extremely limited in being able to assist in remedying after the fact.

By knowing when to be proactive with a call to the manufacturer, installers can mitigate many types of potential pitfalls. And if you’re just not sure, it’s best to call.

For more information on metal roof and wall products and training, MBCI offers courses through its Metal Institute. These courses are available for general training purposes or for those seeking installer certification.

Fire Resistance for Insulated Metal Panels

When it comes to understanding fire ratings for wall panels on buildings, one of the first things to overcome is incorrect information or misunderstanding that sometimes emerges around this topic. In an effort to achieve some greater clarity, let’s look at some of the basics of fire resistance ratings, particularly for insulated metal panels (IMPs).

Building Code Requirements

The fundamental reason that any wall needs to provide some degree of fire resistance is to allow people enough time to safely evacuate from a space or building in the event of a fire, or to prevent the spread of fire between defined areas or whole structures. Building and fire codes have been developed and adopted, in part, specifically to define the situations, building types, conditions and circumstances where different degrees of fire resistance are required to protect the public health, safety and welfare. Therefore, when looking at a specific building and the fire resistance ratings required, the applicable codes must be consulted and the proper determination made regarding the minimum fire resistance requirements for the different exterior and interior walls of that building.

Ratings-Based on Testing

The established means for knowing whether or not a wall meets a particular fire resistance rating is based on conducting a fire test in an independent laboratory. For IMPs, that means a manufacturer needs to submit full-size product samples to a laboratory such as Underwriter’s Laboratories (UL), which will then prepare and carry out the test according to standard, agreed-upon procedures such as ANSI/UL 263, “Standard for Fire Tests of Building Construction and Materials.” The procedures dictated by a standard such as this are intended to be the same for all similarly tested materials or products to determine the actual fire resistance rating for each. When the products are subjected to the prescribed heat and flame under uniform laboratory conditions, then they can be classified based on how well they performed. Some products, for example, may survive the test long enough to qualify for a 1- or 2-hour rating, while others may only qualify for a 30-minute rating before succumbing to the fire.

Urology Medical Office Building MBCI
The Urology Medical Office Building in Virginia Beach, Virginia utilizes 7.2 Insul-Rib® and CF Architectural – Horizontal insulated metal panels. View the product data sheets for these products for information on their fire resistance ratings.

Selecting Products

In creating or renovating a building, then, it is incumbent on the design and construction team to choose products and materials that have a proven, tested fire rating that meets or exceeds the building code requirements for the particular building at hand. If a manufacturer of IMPs has been identified ahead of time, then it may be possible to ask for evidence of the UL or similar test to prove that the selected product or assembly meets the code requirements. But many times, there is a need to first determine the requirements, and then look for the available products and manufacturers who can provide the needed fire resistance. Fortunately, UL maintains an online directory of all of the products that they have tested and certified. Their online certifications directory allows users to input selected criteria to search for specific result reports. Using this resource for IMPs, the UL Category Code of BXUV and the UL File Number of U050 should be entered to do a search. This will yield a summary list referencing the ANSU/UL263 test with a link to the BXUV.U050 test report for IMPs. There you will see under item 2: “Metal faced panels, nominal 42 in. wide by nominal 4 in. thick (for the 1 Hour Rating) nominal 7 in. thick (for the 2 Hour Rating) or nominal 8 in. thick (for the 3 hour rating) installed vertically or horizontally. Panels supplied factory double tongue and grove joint.” This lets the design and construction know that 1-, 2-, or 3-hour ratings are available depending on the thickness of the IMP and given that the factory joint is provided. Hence, the manufacturer can label their products accordingly.

By specifying and selecting the proper products that have been correctly tested and certified, then building code compliance is not only streamlined, the building will meet the inherent fire and safety requirements for the people who will occupy it.

For fire resistance information on MBCI panels, please review the product data sheets.

Combatting Thermal Bridging with Insulated Metal Panels

When using compressible insulation, say for instance fiberglass batt, consideration must be given to how that insulation is going to be deployed in the actual wall or roof. For instance, installers might place the insulation across the framing members and then smash it down with the cladding and run a screw through to the underlying structure. The problem here is that the insulation is rated with some R-value—and that R-value is determined by an ASTM procedure that also determines what its tested density is. So in essence, it’s ‘fluffy’ insulation.

One manufacturer’s insulation, however, might be thicker than another’s. The contractor is buying an R-value, not a density or a thickness. The insulation is tested to that R-value at whatever thickness and density¹ is needed to achieve it. Let’s say R-19 fiberglass batt is specified, but then it is put in an assembly and smashed down flat… now it’s not R-19 anymore; it’s now R-something else. That’s a thermal bridge—when the insulation’s R-value has been compromised.

Manufacturers have the ability to run long length panels that minimize the number of end joints. This continuity provides significant advantages over traditional insulated materials when designing for energy efficiency. This image illustrates the difference between fiberglass batting made discontinuous by compression between panel and framing members and the continuous insulation provided by insulated metal panels.

Unfortunately, thermal bridging is almost impossible to eliminate. In the example above, another choice might be to put it between studs. Except in this situation, the studs break the insulation. While it’s not pinched, the studs are separating it. Whether the studs are metal or wood, in either case it’s still a significant thermal short circuit or a thermal bridge.

Even with the highest quality insulation systems—insulated metal panels, for example—a joint is required. Building is not possible without putting neighboring panels together. Therefore, insulation is discontinuous. While it’s impossible to avoid thermal bridging, there are two requirements to ensure the building performs the way it needs to perform.

  1. Thermal bridging must be mitigated. In other words, the designer or installer has to try to eliminate as much of it as possible.
  2. If thermal bridging is unavoidable, it must be accounted for in some fashion, which usually means putting more insulation somewhere to make up the difference. This is called a “trade-off” and is allowed by most building energy efficiency codes.²

Why Insulated Metal Panels?

Insulated metal panels then are the best bet, because although the joint is a thermal bridge, in effect, it is not nearly as impactful as breaking a line of fiberglass with a stud or smashing the fiberglass between the panel and a framing member. In the illustration below, R-value doesn’t just vary at that point where the panel and the stud meet. The entire insulation line gets smashed and one would have to go some distance from the stud before the insulation returns to its normal, fluffy thickness. These issues need to be mitigated and accounted for.

assembled side joint
Continuous insulation is critically important to an efficient envelope design. Insulated metal panels, with their side laps designed for concealed fasteners, eliminate the possibility of gaps in the insulation and thermal bridges. Continuous insulation is important because thermal bridges and discontinuities introduced by compressing non-rigid insulations cause the in-place R-Value of the assembly to be less than the tested R-Value of the insulation used. This effect has become a focus in newer energy efficiency codes such as ASHRAE 90.1 and IECC.

Manufacturers such as MBCI and Metl-Span publish insulated metal panels as U-factors because the joint is tested as part of the assembly (both mitigating and accounting for the aforementioned issues). These values can be found on product data sheets and technical bulletins, such as Metl-Span’s Insulation Values technical bulletin, published January 2017.

References

  1. ASTM C 665 – 12, Standard Specification for Mineral-Fiber Blanket Thermal Insulation for Light Frame Construction and Manufactured Housing, Table 1, Footnote c.
  2. ASHRAE 90.1 – 13, Energy Standard for Buildings Except Low-Ride Residential Buildings, Section 5.6
  3. High Performance Green Building Products – INSMP2A (CEU)

Beauty and Braun: The Benefits of Mixing Insulated Metal Panels with Single-Skin Panels in Commercial Design

Commercial projects aren’t one size fits all. By bringing in metal panel products to suit the individual need, designers and architects can provide custom solutions for a variety of applications. Single-skin metal panels and insulated metal panels (IMPs), if used correctly, can together add both aesthetic and functional value to your projects.

While IMPs can provide superior performance with regard to water control, air control, vapor control and thermal control, you may sometimes find your project requires—from an aesthetic perspective—the greater range of choices available in single-skin profiles. Let’s spend a little time looking at some of the reasons behind the growing trend of specifying a combination of insulated metal and single-skin panels.

Benefits of Insulated Metal Panels

Insulated metal panels are lightweight, composite exterior wall and roof panels that have metal skins and an insulating foam core. Their much-touted benefits include:

  • Superior insulating properties
  • Excellent spanning capabilities
  • Insulation and cladding all in one, which often equates to a shorter installation time and cost savings

Benefits of Single Skin

Single-skin panels, on the other hand, with their expansive array of colors, textures and profiles, may have more sophisticated aesthetics. They can be used on their own or in combination with IMPs. It should be noted, too, that single-skin panels can—in their own right (as long as the necessary insulation is incorporated) —satisfy technical and code requirements, depending on the application.

Beyond aesthetics, when it comes to design options, single-skin products offer a wide range of metal roof systems, including standing seam roof panel, curved, and even through-fastened systems. As for wall systems, those may include concealed fastened panels, interior wall and liner panels, and even canopies and soffits, not to mention exposed fastened systems. Therefore, you have a wide range of not only aesthetics options but VE (Value Engineering) options as well.

Why Mix?

So, in what situations might the designer or architect choose to combine the two panel types? Let’s examine a couple of specific scenarios related to the automotive or self-storage worlds as a means of illustration. In both of these types of applications, it is not uncommon for the designer to recognize the importance of wanting to keep the “look” of the building consistent with branding or to bring in other design elements.

Coalville Wastewater Treatment Facility
The Coalville Wastewater Treatment Facility in Logan, Utah combines the insulated CFR panel with the single-skin Artison L-12 panel.

Single-skin panels can be used as a rain screen system in the front of the building or over the office area, and would provide the greater number of design options. In the rest of the building, designers can take advantage of the strength, durability and insulation benefits of IMPs. Although you could use one or the other for these examples, the advantage of mixing the two would be achieving a certain look afforded by the profiles of single-skin, while still adhering to stringent building codes and reducing installation time—which is the practical part of using IMPs.

Focus on HPCI IMP Systems

One great example of a current trend we’re seeing at MBCI is the use of the HPCI-barrier IMP system, along with single-skin panels. The High Performance Continuous Insulation (HPCI) system is a single system that is a practical and effective replacement for the numerous barrier components found in traditional building envelopes.

HPCI Insulated Metal Panels
The HPCI Insulated Metal Panel is quick and easy to install and provides an economical solution to conventional air, water, thermal and vapor control without sacrificing thermal efficiency.

A big benefit to using the HPCI system is that the barrier wall is already in place. In terms of schedule, the HPCI barrier system is typically installed by contractors who are also installing the single-skin system, eliminating the need for multiple work crews, and thereby minimizing construction debris and reducing the likelihood of improper installation. With a general lead time of four to six weeks for the HPCI and a week or two for the single-skin, the installation goes fairly quickly. Therefore, it appeals as the best of all worlds—a single system meeting air, water, thermal and vapor codes (ex.: IBC 2016, NSTA fire standards) plus the design flexibility of a single-skin rain screen product. (Note: The HPCI panel must be separated from the interior of the building by an approved thermal barrier of 0.5″ (12.7mm) gypsum wallboard to meet IBC requirements.)

Bottom line, HPCI design features and benefits include the following:

• Provides air, water, thermal and vapor barrier in one step
• Allows you to use multiple façade options while maintaining thermal efficiency
• Easy and fast installation, with reduced construction and labor costs

Conclusion

As designers, architects and owners are getting smarter about a “fewer steps, smarter dollars” concept and an increased awareness of applicable codes and standards, not to mention lifecycle costs, the trend towards maximizing the strengths of available systems will continue to grow. Whether the right choice is an IMP system, single-skin or some combination, the possibilities are virtually endless.

Fastener Compatibility with Metal Roof and Wall Panels

The installation of a new metal roof or wall panel on a residential home, business or commercial building takes care, precision and—of course—the right tools. Regardless of the structure, you’ll likely find that choosing the correct mechanical fastener plays a key role in the long-term performance, durability and efficacy of the project.

Many metal roof and wall panels, in fact, rely upon the use of quality mechanical fasteners to secure components to a structure. In order to guarantee a resilient and weather-tight attachment, it behooves the user to select an appropriately compatible fastener type for the specific metal construction, thereby ensuring expected benefits, such as energy efficiency, extended life cycle, and even lowering insurance bills for the owner. In other words, once the decision has been made to use metal building materials for your roof or wall project, the next step is figuring out how to hold it all together.

Know Your Fastener Options

Before selecting fasteners for the project, it is important for the designer or installer to understand the various materials and options available. Typically, this involves the following considerations:

  • What type of material and coating is appropriate?
  • What type of head do I need? Does it need to be painted?
  • Do I need a washer? If so, what material should I use?
  • Should I use self-tapping or self-drilling screws?
  • What thread count should I specify?
  • How long does the fastener need to be?
Many Types of Fasteners
The MCA provides a summary of the different types of fasteners in their technical bulletin, Fastener Compatibility with Profiled Metal Roof and Wall Panels.

Select a Fastener on the Basis of Material

Most fasteners are made from coated metal but both the type of metal and coating must be chosen on the basis of the materials the fastener is bringing together. Galvanic action between dissimilar metals can cause premature fastener failure and lead to leakage. Even stainless steel screws will corrode severely under the right (or actually wrong) conditions. In extreme exposure, sometimes the best option is to use galvanized screws and plan on replacing them at a later date with a larger screw once the zinc has been depleted.

Considerations for Self-Drilling Screws

Self-drilling screws have a drill bit built in and don’t require a pre-drilled hole. Although self-drillers save the installer the step of drilling a hole, they are not always a good idea. The available space between the back of the hole and the next physical restriction must be at least as big as the bit itself or the threads will not engage. Also, drilling a hole allows a quick inspection to ensure the hole is in the correct location and plies are aligned and parallel. Generally, self-drillers are used when going through thin gauge steel into thicker gauge steel and self-tappers are used when fastening two thin gauge plies.

Washers

Fasteners may be used with or without washers. While plastic washers help prevent leaks, they are not required on purely structural connections. When using washers, it is important to visually inspect the screw after installation to be sure they are properly compressed and not kinked. Exposed plastics generally degrade when exposed to ultraviolet light. Furthermore, use of neoprene washers may be prevented by restricted material lists, or “red lists.” Fastener heads themselves may be made of different materials than the rest of the screw, long-life ZAC heads being the most common example.

Fastener Profiles

Fasteners have different profiles. Flat or “pancake” screws are used when low profile installation is necessary and may have Philips, hex, or Torx sockets. Which socket to use is usually an installer’s preference based on accessibility restrictions. Another common feature is an over-sized dome beneath the head to encompass a larger washer. Also called shoulder screws, these screws are useful when thermal movement might distort the holes.

Colored Fasteners for Metal Roofs
Fasteners can also be colored to match the roof or wall panel.

Thread Count per Inch

Thread count per inch, or TPI, must also be considered. Most commonly, fasteners are installed through the thinner ply first and grip in the thicker ply, pulling the plies together. Therefore, TPI selection is usually driven by the thickness of the thicker ply. Generally, the TPI is close to the gauge of the metal for gauge steel and higher for plate and sheet.

Length

The fastener must also be long enough to fully engage all plies of material, plus the length of the drill bit in the case of self-drillers. Generally, this is rounded up to the next half or quarter inch. However, the longer the screw, the more torsional strain is produced during driving and in the case of very long fasteners, this can break the fastener or introduce wobble, leading to poor installation. Therefore, stainless steel with over-sized washers is often used for long screws for added strength and protection.

For More Information on Fastener Compatibility

To learn more about fasteners and their compatibility with different types of metal roof or wall panels, check out Metal Construction Association’s recently published technical bulletin, Fastener Compatibility with Profiled Metal Roof and Wall Panels.

A Storehouse of Storage Solutions

With more than an estimated 54,000 storage units spread across the U.S. in 2015, according to IBISWorld, and 2.63 billion square feet of existing rentable self-storage space in 2014, the self-storage industry is booming. In fact, U.S. storage facility revenue topped off at an estimated $29.8 billion in 2014, rising to $31 billion in 2015 and is expected to reach $32.7 billion in 2016. In this growing market, storage builders and facility owners face increased competition and must build and maintain more efficiently and effectively than ever. Metal panels can be a differentiator for this market, especially through multi-story and climate controlled storage facilities.

MBCI Self Storage
Southlake Self Storage in Weatherford, Tex. is a multi-story storage facility utilizing MBCI’s PBU, PBD and PBR metal panels.

Maximizing Sustainable, Rentable Space

Among the cladding and roofing materials available to build these specialized facilities, insulated metal panels (IMPs) are highly energy efficient, deliver a full weather barrier and can be designed without exterior wall framing. This boosts rentable square footage by eliminating exterior wall framing typically built with studs, batt insulation, and liner panels.

Made from 90 percent closed foam, encapsulated inside of two metal panels and impervious to water, IMPs offer a high R-value, which is a big benefit for all storage types, particularly cold storage facilities. Steel panel facings create a vapor barrier and provide long-term thermal stability, virtually eliminating off-gassing found with rigid board insulation. IMPs give design professionals the opportunity to design functional, attractive, sustainable storage facilities, and facility owners the opportunity to lower construction, operating, energy consumption, and maintenance costs throughout the life span of a building.

As an all-in-one air solution—delivering an air, vapor and water barrier with continuous insulation—building teams can strip down the multiple trades to one single application. This means there are no gaps or voids to sap thermal value, and no degradation by air or moisture. Furthermore, IMPs are the most efficient product available, providing an R-value of 7 to 8 per inch vs. the 4.5 for batt insulation, essentially doubling performance. So not only do building teams come away with a thermally superior product, but the IMP storage facility will meet increasing continuous insulation code requirements, such as those mandated by ASHRAE 90.1.

Of course, increasing rentable square footage is one of the biggest draws about IMPs for building owners as those extra four to six inches on the perimeter go straight to the bottom line.

A Modern Style for Storage

Evolving from the standard-looking, plain boxes, today’s storage facilities are taking on a more architectural look to better blend into the office complexes, residential communities and retail complexes surrounding them.

With a variety of high-performance coatings, colors, reveal joints and corrugated sheets with assorted patterns, IMPs offer a large selection of design options to architects looking to create these more trendy designs.

Metal Panels for Self-Storage Buildings
A-AAAKey Mini Storage in utilizes modern colors with 55,000 sq. ft. of MBCI’s Ultra-Dek® metal roof panels.

“The calculated use of smooth, concealed-fastener panels harkens to contemporary design styles with an eye toward the future,” states Ryan Rogers, managing partner, RHW Capital Management Group, Orange, Calif., in an Aug. 2016 issue of Inside Self-Storage. “This can create the perception of innovation and dynamism, communicating to customers that your facility is on the cutting edge of the industry and, as such, a successful leader.”

In order to capitalize on the design and performance options leveraged by IMP panels, architects are advised to integrate these systems from the project’s onset in order to maximize efficiencies and potentially take advantage of longer stands, greater distances and heavier steel gauges.

Multi-Level Storage Facilities

Moving forward, designers can expect to see an increase in multi-story storage facilities, particularly in urban areas, where building owners are being forced onto smaller lots.

Explaining the trend in a Sept. 2016 issue of Commercial Investment Real Estate magazine, Michael Haugh, CCIM, senior director of revenue management, Storage USA, Memphis, states, “Increased land costs have forced developers to build up, particularly in urban markets where land tracks of four or more acres necessary for single-story developments are nonexistent. In some cases, a multistory project can be built on as little as 1.5 acres.”

Or in regions where there is little space for new construction but a high demand for storage, like New York City, storage companies are renovating upward. For example, Stop & Stor partners with door and storage solution company, DBCI to convert existing buildings into high-end, multi-level storage facilities. Using existing building blueprints and outline unit placement, DBCI created a custom storage solution in a space that is both conveniently located and functional For more information, read “Urban Storage Units” in Metal Architecture’s Jan. 2016 issue.

Filling the Storage Niche

From multiple stories to designer-end architecture, IMPs are actively filling an important niche in the self-storage industry as a durable and aesthetic, all-in-one building enclosure solution.

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