Tag: building code
Metal Panel Roof Restoration & Installation
Overhead Door Considerations for Metal Buildings
Selecting the right overhead door shouldn’t be an afterthought. As with metal panels, they should be a key consideration when planning and designing a commercial or industrial metal building. Functionality (i.e., size, operation and environmental concerns), security and quality are priority factors. In addition, location, climate and building codes should also be part of the overhead door solution decision. Selecting a door type and framing, in fact, can further depend on end use, strength/longevity needs, access and clearance/framing restrictions. Additionally, the type of door requested or required will impact the framing and support needed for installation.
With these criteria in mind, its of note that metal building manufacturers don’t always supply the overhead doors for a project. Therefore, ensuring compatibility and optimal performance requires viewing door options from top to bottom and side to side—figuratively and literally.
Overhead Door Types
Although MBCI primarily offers roll-up doors, these are not the only door options for metal buildings. The primary types of commercial doors for large metal building openings can include the following:
- Roll-Up Doors aka coiling/drum doors are typically a continuous corrugated sheet that nests into itself as its rolled around a cylindrical drum at the top of the door opening. This nesting allows them to take up far less overhead space as compared to doors that slide on tracks. Generally less expensive to purchase, roll-up doors also boast durability, maintenance and longevity benefits.
- Sectional Doors are typically smaller horizontal door leafs/ panels hinged together and mounted between two tracks on both sides of the door. This permits the sections to be lifted continuously either by transitioning horizontally back into the building above the door opening or vertically only above the opening, clearance permitting.
- Vertical or Horizontal Bi-Fold Doors are similar to sectional doors but have much larger panel sections, requiring fewer door panels. Manual operation is an option, however operation most often occurs via hydraulics with the support of door headers or jambs only and not via a full track system.
- Sliding Doors may be mounted via an external or internal horizontal track system at the top of a frame’s opening. Depending on door weight and size, sliding doors may rely on support from the top track system or lower guide rail mounts and wheels as well. Top-mount-only systems are prevalent on smaller commercial doors or in agricultural uses. Larger versions typically support industrial applications like airplane hangars and freight facilities.
- Walk Doors/ Man Doors are common to metal buildings of all sizes and types As a primary means of entry and exit. MBCI offers walk doors in varying sizes for commercial and industrial and agricultural building applications.
Planning Ahead: Coordination Is Key
Once you’ve selected the overhead door type best suited to your project, coordination with the building manufacturer is a must. Specifically, be certain that the building manufacturer knows the type and size of your doors before ordering your building materials. Here are some factors and situations you will want to account for:
- Door Opening Size: Allow ample space to ensure no obstructions when the door is in its maximum open position. Even partial obstructions may require building design adjustments to accommodate for larger openings.
- Door System Weight: The weight of the entire door system—including framing, sheeting, hardware and drive systems (if applicable)—can require certain design considerations.
- Clearances: When open, the horizontal and vertical panel clearances shouldn’t foul trims or building exterior cladding.
- Installation Clearances: Be sure to understand minimum interior building clear heights needed if installation of track systems are necessary. Or, if using roll-up doors, account for drum clearance and its proximity to roof framing, ceiling liners or roof insulation.
- Framing Materials: Be sure surfaces and flanges of framing materials are wide enough for proper attachment of door tracks. The same goes for mounting hardware and mechanical operators if so equipped and required.
- Bracing: If appropriate, evaluate any supplemental bracing necessary to keep the door opening square. Additionally, support for the door sheet in all positions should also be a consideration.
- Verify Manufacturer Requirements: Work with the door supplier and advise the building materials manufacturer if the door opening, framing and/support require minimum or maximum deflections/limits. This helps ensure proper operation when building framing deflects under various loadings. Failure to do so may prevent the door from opening or closing properly. This coordination is made easier when the same manufacturer providing the roof and wall materials also provides the overhead doors.
In Conclusion
Always ensure you’re getting high quality metal overhead door products and services that seamlessly integrate into new or existing metal building projects. Regardless of scope, MBCI can help you find the best overhead door solution suited to your needs and project specifications. Contact MBCI today!
Cutting Metal Panels Properly On Site
Cutting metal panels on site is an often-necessary part of installing metal roofing and wall panels. However, using the right tools and methods to ensure the panels remain damage-free is vital. Using the wrong tools can result in rust, rust stains, the voiding of warranties and diminished building service life. In this blog post, we’ll share several common field-cutting techniques and best practices that help ensure good results.
Maintaining Longevity When Cutting Metal Panels On Site
When metal panels are made in a manufacturing facility, the tools and methods used to cut the coated metal coil help protect the cut edge from deterioration like corrosion. When cutting metal panels on a jobsite or in the field, protecting any cut edges is just as important. To understand how to field-cut metal panels without sacrificing the quality and protection delivered from the manufacturing facility, you must first understand the what protects the panels. Most often, metal roof and wall panels are fabricated from Galvalume®-coated steel coil because of its proven longevity. Not only does the Galvalume coating protect the surface area of the metal panels, it has also been shown to be effective along the thin edges of the metal too, as long as those edges are cut properly.
During fabrication, the Galvalume metal panels are cut to length either by shearing while flat before entering the roll former, or by means of a profile shear as the panels exit the roll former. Either method tends to “wipe” the Galvalume coating across the cut edge of the metal panels. This provides superior cut-edge protection from corrosion.
Likewise, when panels arrive on site, any needed field cutting should address the same concerns of protecting the edge of the steel from corrosion. Of course, there are ways of doing the field cutting correctly. However, there are also poor strategies that can lead to real problems. The following are examples of common field cutting tools and the best practices for good results.
Common Tools and Methods for Cutting Metal Panels On Site:
Aviation Snips
Red and green aviation snips are a good choice for small cuts on metal panels, such as around pipe penetrations. These snips will wipe the Galvalume® coating in the same way as factory shears, making them a good choice.
Electric Shears
Electric shears are optimal when making lengthier cuts along the steel, such as cutting a wall panel at a corner or at a door opening. These shears take a ¼” strip of metal out of the panel during the cutting process, which tends to leave both sides of the panel smooth and flat along the cut. Like the aviation snips and factory shears, electric shears will wipe the Galvalume coating and protect the edges.
Mechanical Shears
Mechanical shears are an add-on tool that fit onto a battery-operated impact or screw gun. These shears do not take any metal out of the panel and will leave a slightly wavy edge. Mechanical shears are an excellent choice for bevel cutting standing-seam panels at hips and valleys, since they too wipe the Galvalume coating over the cut edges to offer protection.
Nibblers
A nibbler is a great tool for cutting across corrugations in wall panels to create openings for windows, doors and similar structural additions. A good nibbler typically costs $500-$700 (currently), but is well worth it if you often cut corrugated metal panels. The punch and die in the nibbler tends to wipe the Galvalume across the cut edge as it punches out small, half-moon shaped pieces of panel. However, because these little metal pieces will fall away from the cut, it’s important to contain them so no one walks on them. Otherwise, they can embed in the soles of installer’s shoes and create scratches in roof panels when they walk on the roof.
Skill Saw
Skill saws are an ideal tool for cutting metal panels because of their versatility. This tool can cut either across or parallel to corrugations, whether straight or at an angle. When using a skill saw, it is critical to use a saw blade that cuts cool. Otherwise, the Galvalume coating can melt along the cut edge and become ineffective. In particular, do not use an abrasive blade, which will generate heat and damage the coating.
Additionally, its vital to avoid cutting panels on the roof or above other panels. A skill saw blade will throw considerable amounts of steel debris into the air and down onto any panels below. This debris, called swarf, will quickly rust and ultimately cause rust spots in the panels. If enough swarf gathers in one spot, it can rust through the panel.
Steel swarf, like this collected at the ridge will rust through the panel.
Which Tools Should To Avoid When Cutting Metal Panels On Site:
Tools that should never be used include:
- Torches
- Cut-off saws
- Reciprocating saws
- Hacksaws
- Grinders
All of these tools will melt the Galvalume® coating, causing edge rust just like an abrasive blade would. These tools also throw a lot of steel debris (swarf) onto the panels they cut. This debris will be hot and will embed into the panel coating. This can cause rust spots and bigger problems down the road.
In conclusion, using the right tools and following metal panel manufacturer recommendations when cutting metal on site will help ensure that the panels remain damage-free and the final installation will be a fairly seamless process. Using the wrong tools can result in rust, rust stains, and the voiding of warranties. For more on best practices and recommendations for on-site cutting and installation of metal panels contact your local MBCI representative.
Understanding LEED for Green Metal Buildings
Designing and constructing sustainable buildings has become a mainstream expectation of most building owners. Whether for reduced energy costs, higher returns on investment, or as an organizational philosophy, “green” building solutions are in demand. Perhaps the best known and most often cited program to achieve these goals is the US Green Building Council’s (USGBC’s) LEED® rating system. While some may think that green buildings are more complicated and costly to build, that is not actually the case. This is especially true when metal building materials are used. In fact, metal buildings are an ideal and economical way to pursue sustainability goals and LEED certification. How? We break it down as follows:
The LEED® Program
The LEED program has been in use since 1998 and is now used worldwide. It is a voluntary, point-based rating system that allows for independent review and certification at different levels. These levels include Certified (40-49 points), Silver (50-59 points), Gold (60-79 points), or Platinum (80 or more points). Since it allows for choices in which points are pursued, innovation and flexibility are entirely possible as long as specific performance criteria are met. It also encourages collaborative and integrative design, construction and operation of the building.
Points are organized into six basic categories, many of which can be addressed through metal building design and construction, as summarized below.
- Location and Transportation: Metal buildings can be manufactured and delivered to virtually any location. That means they can support LEED criteria for being located near neighborhoods with diverse uses, available mass transit, bicycle trails, or other sustainable amenities. Metal building parking areas can also be designed to promote sustainable practices for green vehicles and reduced pavement. This all contributes toward obtaining LEED eligibility.
- Sustainable Sites: Adding a building to any site will certainly impact the natural environment already there. Delivering portions of a pre-engineered metal building package in a sequence to arrive as needed means that the staging area on-site can be minimized—reducing site impacts. Additionally, using a “cool metal roof” has been shown to reduce “heat island” effects on the surrounding site and also qualify for LEED.
- Water Efficiency: Any design that reduces or eliminates the need for irrigation of plantings and other outdoor water uses is preferred. Incorporating metal roofing with gutters and downspouts, as is commonly done on metal buildings, allows opportunities to capture rainwater for irrigation or other uses. It also helps control water run-off from the roof and assists with good storm water control.
- Energy and Atmosphere: Metal buildings can truly shine in this category. Creating a well-insulated and air-sealed building enclosure is the most important and cost-effective step in creating an energy conserving building. A variety of insulation methods for metal building roof and wall systems are used to achieve this. Typically, metal building construction uses one or more layers of fiberglass insulation and liners combined with sealant and air barriers. Alternatively, insulated metal panels (IMPs) provide all of these layers in a single manufactured sandwich panel with impressive performance. Windows, skylights and translucent roof panels can provide natural daylight, allowing electric lighting to be dimmed or turned off. For buildings seeking to generate their own electricity, standing-seam metal roofing provides an ideal opportunity for the simplified installation of solar photovoltaic (PV) systems. Metal roofs generally provide a sustainable service life in excess of 40 years. This means they can outlast the PV array, thus avoiding costly roof replacements during most PV array lifespans.
- Materials and Resources: Life Cycle Assessments (LCAs) are recognized by LEED as the most effective means to holistically assess the impacts that materials and processes have on the environment and on people. Fortunately, the Metal Building Manufacturer’s Association (MBMA) has collaborated with the Athena Sustainable Materials Institute and UL Environment to develop an industry-wide life cycle assessment report. There is also an Athena Impact Estimator that can help with providing LEED documentation. Metal buildings support exceptional environmental performance through the significant use of recycled steel and the reduced need for energy intensive concrete due to lighter weight buildings.
- Indoor Environmental Quality: Most people spend much more time indoors than outside, which impacts human health. Therefore, LEED promotes or requires using materials that don’t contain or emit harmful substances. It also promotes design options for natural daylight, exterior views and acoustical control to promote psychological and emotional well-being. Metal buildings are routinely designed to readily incorporate components that help achieve these indoor qualities.
In addition, some LEED points are available for demonstrating innovation and addressing priorities within a geographic region.
Considering the qualities listed above, metal buildings clearly provide a prime opportunity to pursue LEED certification at any level. To find out more about the LEED rating system, visit https://new.usgbc.org/leed. To find out more about successfully designing and constructing metal buildings pursuing LEED certification, contact your local MBCI representative.
A Guide to Selecting the Right Metal Roof Panel
With the great variety on the market, one of the main questions we, as metal roof panel manufacturers, get from customers is “How do I select the right panel for my project?” The answer can generally be found by examining a number of criteria, including the properties of the roof, the region and climate, geometry, slope, warranty type…among other key factors.
Here we will provide a brief overview of the various factors that should be considered when narrowing down the choices.
Determining Factors
1. Slope— Slope is the first consideration as just this one aspect will eliminate certain panels, making it easier to narrow down options right from the start. The two types of roof slopes are low slope and steep slope.
- A low-slope roof, commonly found in commercial applications, is one whose slope is less than 3:12. The benefits include a simpler geometry that is often much less expensive to construct, and the requirement of fewer materials than a steep slope, thereby reducing material costs.
- A steep slope roof, more common in residential construction, is one whose slope is greater than 3:12. Steeper slopes are ideal for areas that have higher snow loads and will also prevent the possibility of ponding water on the roof. Since the roof is a visible part of the structure, choosing a metal roof for residential construction often skews more toward aesthetic considerations.
2. Location/Climate— The location and climate of the project is a factor, specifically when looking at certifications/regulatory product approvals, which will limit the panels you can you use within specific regions. This is most relevant to Dade County, the state of Florida, and the Texas Coast, as well as certain snow regions.
3. Specified test standards—Often times, you may need to specify UL 580 or Factory Mutual Insurance Design.
4. Engineering Design—Due to the roof pressure acting on the buildings, engineering design factors eliminate some products because they’re simply not strong enough. This is an area that needs true technical expertise. For that reason, make sure to get a professional engineer to design the roof system in order to determine the correct panel for the project. Also, check with the manufacturer to determine if they have panels that have been tested to certain test standards. If they do not have the testing on a product, that in itself can exclude a particular panel.
5. Geometry—In its most basic terms, roof geometry is an overview of what the finished roof will look like, including special conditions, such as hips, valleys and ridges. The various conditions that go along with specific roof types will determine if a roof geometry is simple or complicated—which will affect the type of panel that can—and can’t—be used. For instance, a Double-Lok® roof panel can be used on a low slope roof—it can go down to 1/4:12. However, if a low roof slope condition has a valley, you may want to avoid a Double-Lok® panel since this product is more difficult to use in a valley situation.
6. Panel type— Panel types can be broken out into two main types: standing seam and through-fastened. The choice of specific product within these general categories depends on a number of considerations, including aesthetics and weathertightness warranties. If your project calls for either standing seam OR through-fastened, that will eliminate about half the types right off the bat.
- Standing Seam Roof Systems
In basic terms, there are four unique styles of metal standing seam panels: Double lock seam, symmetrical seam, one-piece snap-lock interlock and two-piece snap-lock interlock. These styles can be further delineated by seam shape or profile, i.e. trapezoidal rib, vertical rib, square rib and tee rib. - Through-Fastened Roof Systems
Exposed, or through-fastened panels, are available in a variety of widths, usually from two to three feet wide. They also come in various rib shapes, heights and spacings. Typical gauges are 29 and 26, but they also come in 24 and 22 gauge. There are also structural and non-structural through-fastened panels. Structural panels are capable of spanning across purlins or other secondary framing members such as joists or beams. Non-structural panels must be installed over a solid deck. Through-fastened roofs are best suited to small- and medium-sized metal buildings and residential applications. In both instances, the panel runs are limited to shorter lengths where thermal movement is typically not a problem.
7. Substrate— Examples of substrates are open framing, plywood, and metal deck. Some panels can’t be attached, for instance, to open framing but almost every type of panel can attach to plywood.
8. Required Weathertightness Warranties— If a weathertightness warranty is a requirement, your options are down to the only panels offered with that guarantee—eliminating all the through-fastened panels.
Looking to the Manufacturer for Help
While specifiers need to take that initial look at all the determining factors, the choices can still feel overwhelming. Once you’ve eliminated the panels that surely won’t work, you will still likely be left with many strong choices. The metal panel manufacturer can guide you to that decision. We encourage you to contact the MBCI team of experts to help further narrow down the choices in order to finalize what is the best metal roof panel for your project. For more guidance on finding the right roof panel for your project, stay tuned for our white paper coming soon.
Doors of Steel: Metal Roll-Up Doors for Any Application
Metal roll-up doors are designed specifically to offer security and durability in a variety of applications. MBCI offers a series of roll-up doors to service the self-storage and commercial markets.
Here, we’ll provide some key product details to help guide you to the right product for your application.
Self-Storage Doors
Built to meet the specific and unique demands of a small structure, MBCI doors offer many standard features that make it a superior choice. These include a proprietary gear-driven tensioning bracket for safe and easy adjustments, a rust-resistant aluminum bottom bar to protect against the elements, and a standard stainless steel latch.
650 Series: The best choice for a low-maintenance, wind-certified self-storage roll-up door.
Transform your storage building’s exterior and protect your tenants’ assets with the 650 Series steel-curtain roll-up door. Wind-load tested in accordance with IBC, FBC, and TDI, the wind-certified 650 Series was engineered to protect and maintain building envelopes in extreme conditions without the heavy, weighted elements required in frequent commercial use. The 650 Series provides tenants and facility or building owners peace of mind with sturdy construction that requires little to no maintenance. Wind-rated up to 8’ 8” and approximately 90 mph, the 650 Series door is ideal in coastal areas that experience large wind gusts and hurricanes and comes with a 30-year film integrity warranty and up to 25-year chalk and fade warranty. Our 650 Series offers insulation for better energy efficiency and is perfect for climate-controlled storage. We also offer top and side draft stop kits to reduce drafts.
690 Series: The premium choice for mini-warehouse and self-storage buildings in areas susceptible to extreme winds.
The 690 Series steel-curtain roll-up door is designed to operate smoothly and perform well in severe weather. They won’t buckle, bow, become misaligned from the tracks, or separate from the door frame during strong storms and wind events. Featuring 16-gauge galvanized steel guides and a wind bar, the 690 Series is wind-rated up to 10’ and approximately 140 mph—ensuring they meet mini-warehouse wind-load requirements. Our metal roll-up doors are wind-load tested in accordance with IBC, FBC, and TDI, allowing facility managers to avoid higher up-front insurance costs and reduce maintenance costs and downtime in the event of a storm. For climate-controlled units, our 690 Series offers insulation to help improve energy efficiency along with our top and side draft kits.
Commercial Series
MBCI’s commercial-grade, steel curtain roll-up doors offer tremendous versatility, and unparalleled quality, are easy to install, and require minimal maintenance. With a variety of models, colors, and mounting options, it is our goal to provide the right door for any application and back it with the best warranty you can find. These commercial doors are available as light gauge and heavy gauge; some options are wind-certified.
Light-duty roll-up doors: Quality roll-up steel doors engineered to withstand frequent use and outperform others in the industry.
MBCI offers two steel roll-up doors ideal for light-duty commercial use in everything from warehouses and farms to recreational storage and auto body shops. Available with electric motors and multiple mounting options, the 1950 Series and 2000 Series are versatile and low maintenance.
1950 Series: Known for operating quietly and requiring less headroom, the 1950 Series door is suitable for a number of light-duty commercial and recreational uses.
2000 Series: The 2000 Series is the perfect door for light-duty applications that require frequent use.
Heavy-duty roll-up doors: The integrity, partnership, and quality behind the design and production of our heavy-duty commercial doors make them the most durable and reliable in the industry.
Perfect for high-traffic use, our heavy-duty, commercial-grade metal roll-up doors are suitable for warehouses, loading docks, terminals, and distribution centers. Our quality sets us apart; every MBCI commercial door features heavy-duty brackets made of a .187-thick angle, high-cycle spring life, and continuous-duty design. Wind-load tested in accordance with IBC, FBC, and TDI, our heavy-duty commercial-grade doors is wind-certified to meet stringent building codes in coastal regions, including Florida and Texas.
2500 Series: Our 2500 Series is a heavy-duty sheet door suitable for warehouse and freight buildings.
3100 Series: Wind-rated and available up to 16′ wide, the 3100 Series will last for years with little to no maintenance.
Wind-certified doors: Commercial metal roll-up doors from MBCI are wind certified to perform against high winds and meet building codes. Fueled by constant changes in local and national building codes, as well as increasing insurance costs, doors with validated wind certification can dramatically reduce maintenance and replacement costs and minimize downtime. MBCI’s wind-certified doors are wind load tested in accordance with BC, FBC, and TDI.
(Note: MBCI’s 2500 and 3100 Series are all wind-certified commercial door options.)
MBCI delivers the highest quality metal roll-up door products and services that seamlessly integrate into new or existing building projects. Regardless of the project scope or wind and weather variables, MBCI has the right solution when it comes to roll-up doors for self-storage or commercial needs. Download our capabilities brochure or contact your local MBCI representative to learn more about which product is right for you.
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.
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.
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.
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.