Upgrading Your Roof with Metal Panels

In a recent blog post, we reviewed key considerations to help a building owner decide whether to repair or replace a damaged roof. In this post, we’ll address some ways metal roofing systems are an advantage when upgrading your roof and restoring your building to “like-new”, weathertight condition.

MBCI Blog: Upgrading Your Roof with Metal Panels

Installing Metal Panels Over Existing Roofing

Some owners are concerned about replacing a roof because they dread the cost of removing the existing roof. This concern is valid in many low-slope roofing situations because the new roofing membrane might not be compatible with the existing one, and could cause premature deterioration. There are, however, metal panels specifically designed to be installed directly over existing roofing. And, many of these retrofit systems can be installed over existing roofs made of metal or other materials. Avoiding removal of the old roof obviously saves on cost. However, it also saves considerable time when installing the new roof. As an exposed-fastener metal roofing system, this retrofit application also requires fewer construction components, further streamlining the installation process.

Retrofit metal panels typically feature a membrane treatment that prevents rust or contaminants from the old building materials from transferring to the new panels. This is a versatile solution for both low- and steep-slope roofs (minimum slope: ½:12). It is also very durable and can feature approvals for use in extreme weather locations, including Florida. Metal panels are available in a variety of colors that enhance the overall design of a building. Often, this “replacement metal over existing roofing” approach is the most cost-effective, even compared to some repairs. Additionally, new roofing is more likely be eligible for a warranty, while repairs rarely, if ever, are.

Upgrading Your Roof with Insulated Metal Panels

Energy conservation is on the mind of many building owners and building code enforcement officals. Therefore, adding insulation when upgrading your roof is often required to adhere to building codes. In this case, applying zee-shaped sub-purlins over the existing roof system helps support a new layer of metal roofing. In between the sub-purlins, insulation can be added to meet or exceed current energy code requirements. This system also eliminates the need to remove the existing roofing while providing an added layer (or more) of insulation to improve the overall energy performance of the building. Insulated metal panels (IMPs) like MBCI’s can help keep buildings cooler in summer and warmer in winter—conserving energy year-round.

Sub-purlin systems can fit any existing metal panel, support new panels, and be made to accommodate many types of insulation between the old and new roofs. They can also  support or incorporate a variety of solar energy systems where desired. Roof panel options include variety of profile shapes, textures and colors to suit aesthetic preferences.

Altering the Roof Slope

In some cases, upgrading your roof means changing the roof slope (i.e., turning a low-slope roof into a steeper-sloped roof). In these cases, metal roofing systems can be the most economical choice. Steel framing (16-ga. to 12-ga.) installed over the existing roof frame creates a sloped plane that can support new metal roofing panels. Note that the existing physical shape of the roof, the existing structural system and other rooftop conditions are usually the biggest factors in the geometry and shape of the new roof. Nonetheless, the beauty of the system is that it can dramatically improve the appearance and drainage of a building’s roof, regardless of whether the substrate is steel, wood or concrete.

Lower-slope applications (1/2: to 2:12) are typically driven by economy and designed to efficiently discharge rainwater from the roof. Higher-slope applications (greater than 2:12) often serve to improve and update the look of an existing building. They achieve this by showcasing the metal roof while also improving its drainage and durability. Once the framing is installed, standing-seam metal panels can be installed over the top, creating a ventilated attic space. This allows space for additional insulation , thus improving the energy performance of the building.

Working with Building Professionals

Any of these options are applicable over an existing metal roofing system. They cab also convert other types of roofing systems to longer-lasting metal roofing, or replace an existing roofing system altogether. Of course, engaging the services of a design professional (architect, engineer, etc.) is always appropriate when considering your options. They can help properly assess existing building conditions and recommend the best overall metal roofing solution from metal panel manufacturers.

To learn more about upgrading your roof system with more durable, longer-lasting, better-draining and easier-to-maintain metal roofing systems, contact your local MBCI representative.

Should You Repair or Replace a Roof? How to Decide

Roofs on buildings of all types are prone to damage, wear, deterioration, or leaks. When this happens, it leaves the owner wondering whether to address the problem through repair or replace the entire roof. How to decide? There are a number of key considerations:

MBCI Blog: Repair or Replace Your Roof?

What is the existing roof type?

Different roofing materials require different construction methods, and range in suitability for various types of building conditions. Low-slope roofs commonly feature either asphalt/bituminous roofing, polymer-based membranes or metal roofing. Each of these roofing types has its own procedures, materials and costs associated with identifying and repairing a leak. Steeper-sloped roofs can feature asphalt shingles or metal roof panels. These have various life-span expectations (metal lasts much longer, for example) and different ways to identify issues. Understanding the existing roofing type is fundamental in deciding on the best course of action.

Is the roof under warranty?

Regardless of the roofing type, there may be a warranty in effect that requires any inspection and repair work to be performed by someone certified or approved by the roofing manufacturer. Otherwise, undertaking an independent repair may render the warranty null and void. Hence, before anyone does any work on the roof, contact the manufacturer and confirm the applicability (or not) of a warranty. At this time, you can also evaluate any other options or conditions for a repair. The advantage of a warranty is that there should be little, if any, cost to the owner to repair the roof as long as the work is done according to the warranty terms. Without a warranty in effect, it’s entirely up to the owner to decide whether to repair or replace the roof.

How old is the roofing?

If the current owner is the original owner of the building, the roof age should be easy to determine. But what if this is a pre-owned building? It is often beneficial to determine how old the roofing is so you can understand any potential service-life trade-off. This will play directly into the cost-efficiency of a repair versus a replacement. If the roof is near the end of its service life, then a repair might not make sense if a full replacement is imminent anyway. If the roof is fairly new, then the question of how long a repair may last is important. Will it need to be repeated again before the roof is ready for replacement, and if so, at what cost?

Where is the actual location of the damage?

Is it really the roofing that’s a problem? Could it be something related—such as edge flashing or seals around a roof penetration (i.e. a chimney, pipe, or rooftop equipment connection)? If the damage is in isolated areas, a simple repair or flashing replacement may be the easiest solution. If the condition is more widespread, however, then a replacement may be more logical to address the larger area(s) affected.

 Is this building in a high-risk area for more damage?

Buildings prone to high winds or other severe weather need a more durable roofing system than areas where the weather is less dramatic. If the building is in a high-risk area, it might be reasonable to avoid relying on repairs and instead go for a full replacement.

Are there other inherent issues?

Sometimes, the roof covering isn’t the root of the problem. For example, Low-slope roofs often experience “ponding,” where water can sit in a slightly depressed or settled section of the roof. This can lead to deterioration and leakage over time which is not the fault of the roofing, but of the structure or insulation beneath it.

Similarly, steeper-slope roofs may be designed with a geometry or penetrations that prevent proper drainage and cause issues due to water backups. Or, perhaps ice build-up in winter is causing problems with the insulation in the roof system. Identifying the proper issue that is causing the problem will allow for selecting the best solution.

Deciding to repair or replace

Answering the basic questions above will likely reveal which approach—repair or replace—is most appropriate. Small areas of damage in areas in low-risk locations may best be served by simple repairs. If there are many years of roof life remaining or a warranty is in effect, this is especially true. However, missing or faulty components, worn or brittle membranes, or rusting metal panels may all be indications to replace the roofing entirely. This is even more important if the roof is quite old, out of warranty, or in a high-risk area.

In our next post, we’ll look at how metal roof systems help solve a variety of problems within different budgets. In the meantime, contact your local MBCI representative to learn more about roofing warranties and roofing systems for buildings.

Are Metal Panels An Ideal Low-Slope Roofing Material?

Many large, commercial, low-rise buildings often don’t benefit from steeply-sloped roofs the way residences and small commercial buildings might. This is because a steep roof slope would add unwanted height and unnecessary construction cost. Buildings like warehouses, retail stores, etc. are more appropriately built with low-slope roofing, commonly known as “flat roofs”. The National Roofing Contractors Association (NRCA) defines low-slope roofs as those with “a slope at or less than 3:12″. Anything steeper qualifies as a “high-slope roof”. With this in mind, let’s look at some key points to consider when designing and constructing a low-slope roof.

MBCI Low-Slope Roofing

 Low-Slope Roofing Materials

When it comes to selecting low-slope roofing products, there are generally three fundamental choices:

  • Asphalt/ Bituminuous Products: The traditional commercial roofing norm for many years, the use of asphalt/bituminous products has dwindled as newer, more appealing options have emerged.
  • Flexible Membrane Roofing: This roofing material can be made from a variety of types of plastic/polymer-based materials (commonly known as EPDM, TPO, PVC, etc.). Rolls of the chosen membrane are laid out on the roof structure and secured in place either with mechanical fasteners (screws with large washers) or with a continuous layer of adhesive.
  • Metal Roofing: Sometimes overlooked, metal roofing is suitable for different roof slopes. Many metal roofs that use standing-seam systems are rated for use with a pitch as low as ½:12.

When considering which type of roofing material to use for a building project, there are a number of significant differences that illustrate why metal roofing is often the ideal choice.

Engineered For Superior Performance

Standing-seam metal roofing is made specifically for use on low-slope roofs as it meets a number of performance requirements:

  • Water resistance: Precipitation doesn’t penetrate through metal or through the standing seams where the metal panels join together. This is why they can tolerate such low slopes, allowing the water to drain away slowly and predictably without leakage.
  • Rigidity: The rigid nature of metal means that there is less opportunity for ponding (standing water). This is not always the case with asphalt/bituminous or membrane roofing systems.
  • Drainage: Metal roofs carry water to the building’s edge toward gutters and downspouts that carry it away from the building. Other roofing systems rely on drainage piped inside the building. This takes up space and has the potential to leak water inside the building and cause damage.
  • Wind Resistance: Standardized uplift testing shows that metal roofing performs as well or better in extreme weather than mechanically-fastened or fully-adhered membrane systems.
  • Durability: The most cited advantage of metal roofing is its long-term strength and durability. Engineered design and use of high-quality coatings ensures a longer lifespan—50 years or more. In contrast, other roofing types typically feature lifespan ratings of 20 or 30 years.
  • Puncture Resistance: Low-slope metal roofing is more puncture-resistant than asphalt/bituminous or membrane roofing. This makes it better able to tolerate foot traffic, hail and other puncture-inducing hazards.
  • Construction/ Installation Ease: Metal roofing panels are custom-made to suit specific building sizes and end uses. This customization typically means it takes less time to place and install metal roofing in the field. Further, metal panels can tolerate a wide range of temperatures and weather conditions and still install and perform as intended. Low-slope roofs are also safer to walk on with less risk of slips, falls and other hazards.

Cost-Effectiveness

Using metal roofing on low-slope roofing systems can be cost effective in a number of ways:

  • Fewer labor hours as a result of the ease of installation saves money during construction.
  • Competitive material costs, particularly if the metal roofing is part of a total metal building package from a single manufacturer.
  • Minimal maintenance requirements and aversion to rusting, mold growth and decay that save the building owner money over time.

This all adds up to a very favorable life-cycle cost.

The performance, cost-effectiveness and life-cycle benefits of metal roofing panels make them a viable option for low-slope roofing systems. Manufacturers like MBCI can help you select the right metal roofing products and provide information and resources to help ensure proper installation.

View examples of low-slope metal roofing projects and contact your local MBCI representative to start your project today.

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:

LEED

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.

Design and Performance Benefits of Insulated Metal Panels

In a prior post on insulated metal panels (IMPs) we reviewed some of the basic things everyone should know about this versatile and lightweight metal building component. In this posting, we will drill down a bit more on the benefits of incorporating IMPs into a new or retrofit construction project. Here are some of the top reasons they are so popularly used in both walls and roofs:

Insulated metal panels (IMPs) are a popular choice for walls and roofs for their energy conservation, durability, longevity and cost-savings.
Insulated metal panels (IMPs) are a popular choice for walls and roofs for their energy conservation, durability, longevity and cost-savings.

Energy Conserving, Space Saving Insulation

Foam plastic insulation is used between the metal skins of IMPs. Such insulation has been accepted for use by building codes for quite awhile provided it meets certain conditions. IMPs have been tested and shown to meet or exceed all code requirements for construction and for energy conservation too. Part of their appeal over other ways to insulate is that they can achieve high performance in a thinner wall or roof assembly than would be required with other types of insulation, such as fiberglass. IMPs are available in thicknesses that range from 2 to 6 inches and have corresponding R-values from R-14 to R-46 allowing design professionals to select the thickness that matches the energy performance level sought in a particular building. Other insulation types would require thicknesses of at least twice as much to approach the same R-values as IMPs. Further, the metal interior and exterior skins are the only finish material needed so the total panel thickness is very space efficient. Thinner IMPs in the walls and roofs can save space in the building or on the site all while achieving high energy performance.

Durability, Longevity, and Low Maintenance

The manufactured panels are rigid and quite strong. They have been tested for compression, tensile, and shear strength with impressive numbers that come about because of the combination of the rigid foam and steel properties. The surfaces are made from the same long-lasting galvanized and factory finished steel used in other metal wall and roof panels so their resistance to weather, abuse, and even harsh conditions has been proven, making them very easy to maintain. In locations where severe weather and storms are a concern, they can also be specified to meet requirements for heavy winds, hail, and similar concerns. Plus, since the skins of the IMPs are made of noncombustible steel, they provide an ignition barrier as part of an overall fire protection scheme for the building.

Cost Saving Construction

IMPs are an “all-in-one” product that takes the place of many other products and components used in traditional construction. Instead of requiring multiple trades and materials to be installed individually over some number of weeks, IMPs are installed by a metal building contractor and allow the walls and roof to be completely closed in with a single trade. The use of concealed fasteners in the side joint of the panels makes installation quick and easy. Unlike other construction systems, the inherent strength and resiliency of IMPs means that work doesn’t need to stop over weather concerns. All of this saves a considerable amount of labor costs and can also save a lot of time meaning buildings can be completed quicker and more economically. It could also mean that an owner is able to occupy and use the building sooner, thus reducing construction financing costs and allowing operations to begin more quickly.

Versatility for Use in Many Building Types

IMPs can be used in virtually any type of new construction and for many retrofit applications too. There is a range of modular panel sizes that can work successfully with different structural elements of the rest of the building. The finished profiles and colors can all be selected to match the design needs of the building with edges, corners, and trim details all based on simple, appealing aesthetics. There are even IMPs specially designed for cold storage or refrigerated space applications. These panels may be part of the building exterior or create an isolated space within a larger building. Either way, they are designed for the rigors of a high use installation.

With such a broad range of benefits and capabilities, you owe it to yourself to check them out for a building project that you may be involved in. The best place to start is by contacting your local MBCI representative, and by signing up for our newsletter to subscribe to our blog.

Why Upgrade a Roof to Metal Panels?

Have you considered using metal panels in building and roofing upgrades? Metal roofing panels from MBCI offer significant advantages over traditional roofing material, including the ability to be integrated with the existing structural system. For buildings that need to comply with strict code requirements, our huge selection of metal roofing can meet your needs.

Save Money with Metal Roofing

Using metal instead of asphalt shingles for roofing provides several cost-saving benefits, including:

  • 60-year lifespan: The strength and durability of metal is unparalleled compared to traditional asphalt shingles, and weathers the elements for a much longer period of time.
  • Sustainability: Our cool roof coatings are extremely energy-efficient, saving you cost associated with heating and cooling your building. With strict requirements in place for buildings today, reducing energy and maintenance costs is top-of-mind, and metal roofing is a simple solution that offers both. MBCI also works with LEED project documentation and has EPDs using LCA results for core panels.
  • Higher Quality Material: From insulated to standing seam and exposed fastening roof panels, our selection of panels are available in gauges ranging from 22 to 29, with a variety of finishes and coatings to ensure your metal roof stands the test of time.
  • Extensive Warranties: MBCI’s signature panels each come with their own unique warranty, with coverage for features including film integrity, chalk and fade, and more depending on the product.

It is important to note that when working with older buildings, there is a possibility of degradation of the subsurface as well as pre-existing structural issues such as overloading the structure.

MBCI's metal roofing panels are a durable and energy-efficient alternative to standard roofing products.
MBCI’s metal roofing panels are a durable and energy-efficient alternative to standard roofing products.

Panels & Systems for Every Application

  • Standing Seam Panels: Commonly used for a variety of commercial, residential, and recreational applications, these are some of the most durable and versatile systems available. We offer everything from mechanically field-seamed panels to curved and snap-together options. No matter what your building is used for, these systems withstand the elements and have fire and impact resistance ratings.
  • Lightweight Panels: MBCI’s product line features lightweight panels that can be used as framing and sheeting materials. For example, the BattenLok® HS is a high strength standing seam roof systems that can be installed directly over the purlins or bar joints. The type of metal paneling chosen for your roofing systems allows for additional customization by being able to choose your color with our extensive color chart. The experts at MBCI have years of experience matching the retrofit roof panels to the new roof membrane.
  • Exposed Fastening: With 9 different styles to choose from, MBCI’s vast selection of exposed fastener roof panels are sure to exceed your expectations. Cost-effective and easy to install, these panels are often used in commercial and agricultural buildings, and are designed for both vertical and horizontal installation.
  • Retrofit Systems: Selecting the correct roofing system is critical in the retrofitting process. MBCI’s NuRoof® retrofit system has the capability to “stick-frame” the current supporting structure. The new retrofit system allows for redistribution of loads while increasing the energy-efficiency of the building. If you prefer installing new panels over existing roofing, the Retro-R® Panel can enable you to skip the removal of the existing roof entirely. This is a great option for saving time and cost related to installation, and can keep your operation up and running with no downtime. The Retro-R® Panel’s Drip Stop membrane prevents rust from old roofs from interfering with new panels, providing a new look with a long life span. With availability in both 26 and 29 gauge Galvalume Plus® and 200 color options, the Retro-R® roofing system is a great option for retrofitting.

To find out more about which metal roofing panel is ideal for your new project or existing building, contact your local MBCI representative.

 

Coordinating Roof Insulation with Metal Building Construction

Energy codes and increasing energy costs have prompted the installation of more roof insulation into metal buildings in recent years to make them more energy efficient. That is fundamentally a good thing and metal building manufacturers have developed ways to accommodate a variety of building enclosure packages that increase energy performance while still being engineered to meet the structural requirements of the building. This allows the whole building envelope to be designed and fabricated so it works as a complete, coordinated system.

Metal Building
Insulation helps maintain a comfortable interior temperature in your metal building during the winter and summer months. 

The metal roofing or metal building suppliers typically don’t design the insulation systems. However, it is important to include them in the discussions or make them aware of what type of system is to be installed. It is not uncommon for a metal building to be ordered with the design stipulation of “insulation by others.” In that case, coordination is needed between the person ordering/designing the insulation system and the metal building manufacturer or roofing supplier. Since there are a great many variables in the way that insulation can be provided, it is not appropriate to think that the design of structural systems (purlins and roof bracing) and cladding systems (clips, fasteners, and metal roofing profiles) will necessarily accommodate all the same insulation in all conditions. Rather, unless the specific details of the insulation system being used in the building are communicated effectively at the time of the order, the manufacturer can not assure compatibility of the systems used with the insulation system that is to be installed.

In order to understand some of the variability in the options, let’s look at some of the common ways that metal buildings are or are not insulated.

Uninsulated Roofs:

Buildings that do not have any heat or air conditioning in them may not need for an insulated roof. This could be true for outdoor shelters, some agricultural buildings, or vehicle storage buildings. However, uninsulated metal roofs have the potential for “roof rumble” as they move due to thermal expansion and contraction, wind, or weather as there is no insulation to mask or deaden this noise. Absence of insulation can also lead to condensation during certain times of the year if temporary heat is added to the building. This condensation builds up and can drop or fall onto whatever is below. Many times condensation issues are mistaken for roof leaks when in fact it’s a mechanical design issue of the building envelope that’s not been properly addressed. If neither sound nor potential condensation are a concern, then there’s no problem. But if either or both need to be avoided, then some basic level of insulation may be prudent.

Over the Purlin Systems:

One of the most common insulation systems for metal buildings and/or open framing systems is to simply install rolls of blanket insulation. In this case, fiberglass insulation with a reinforced liner is draped over structural beams and purlins. The rolls are supplied to length by the insulation supplier based upon the roof structural layout and the required “R” value necessary for the building envelope in thicknesses that can vary from 3″ to 12″. Is is this thickness to be installed over open framing that the metal building/roofing supplier must be made aware of. Based on this thickness, the panel profile can be verified to determine if it can be used as well as confirmation of the correct clip heights and screw lengths for installation. Keep in mind that the supplier will offer a guide to the installer based upon insulation thickness. As insulation can vary by manufacturer, it will be up to the installer to make adjustments as needed in the field to ensure proper placement and hold modularity of the steel system. (See Respect the Module: Metal Roofing Panels are Modular for Good Reason)

Cavity Fill Insulation Systems:

When higher “R” values are required for roof insulation, a single layer over the open framing system may not be sufficient. When that occurs, the designers of the building envelope may need to employ the framing cavity to add more insulation. There are also variation on the cavity fill approach.

One means is to simply introduce a second layer of unfaced blanket on top of the faced insulation. Sometimes referred to as a “sag and bag” approach, here the first layer of insulation over the purlins is ordered to accommodate larger amounts of drape between the roof structure to permit another layer of unfaced insulation to be added on top. This increases the insulation thickness between the purlins but keeps it thin enough to be compressed to accommodate the roof panel installation. For coordination purposes, the thickness of this upper insulation over the purlins needs to be known by the building manufacturer so the clips and fasteners can be properly sized. Likewise, the amount of insulation draping between the purlins needs to be known to determine if purling bracing or other accessories may potentially interfere with the insulation installation.

Other types of cavity fill system may include a faced batt or face roll insulation with long tabs, which are secured to the tops of roof purlins and nest fully into the purlin cavity to fill the space more effectively. This helps in eliminating greater compression of multiple layers of insulation on top of the purlins and permits an additional layer of unfaced insulation on top of the roof structures and/or a thermal spacer block. This system may also require some intermediate banding to support the insulation between the primary supports.

A liner system may be installed that employs a continuous vapor retardent material. This liner is secured to the bottom of the roof structure and additionally supported with metal banding allowing the cavity to then be filled with unfaced insulation between the purlins. More unfaced insulation can also be added on top of the purlins as well. In all of the cases where cavity fill systems are used, it is important to advise the building manufacturer/roof supplier which type is being used to ensure proper panel clip heights and screw lengths. This is important because these systems can and will interfere with the roof structural bracing making them more difficult to install. The metal building supplier may be able to offer bracing alternatives or remedies to eliminate some or all of the bracing that would otherwise be in the way when installing the roof insulation. There may also be suggestions on how to avoid impeding or penetrating the vapor barriers which could lead to condensation issues. Overall, it is best to discuss and coordinate all of these items ahead of time.

Rigid Board/ Composite Systems:

In this insulation approach, rigid foam insulation board is used to achieve the sought after energy performance. Commonly, these use metal deck panels over the roof structure thus supporting the insulation and a vapor retardant material on top of the deck. The insulation and the metal roofing can then be secured to the framing substructure or to the metal deck itself, which means the details of attachment need to be reviewed and engineered to avoid adverse affects on the roofing system.

Metal Building
Minimum decking gauge, clips spacing and clip screw lengths should be considered as well as associated adjustments to labor costs.

Spray-on Insulation:

All of the above systems typically require attention to providing additional air and vapor barriers and proper cutting and fitting during installation so as not to cause unwanted infiltration or to prevent condensation from occurring. For these reasons and more, some people will consider the use of closed cell spray-on foam insulation, which can continuously provide all of these features in one product. It can also be installed after the roof is completed and structure is weathertight.

Metal Building
Any corrosion of the panel due to adhesion of the insulation is not covered by the panel.

In the case of metal buildings, spray-on insulation is typically applied in the field onto the inside face of installed roof panels and sometimes wall panels too. There are, however, a few concerns with this approach in metal buildings. First, if conditions are not right and the panels are not properly prepared, then the spray foam can, in fact, trap moisture between the insulation and the metal components it is sprayed onto. That can lead to corrosion of the metal or deterioration of the insulation. Secondly, not all spray foams on the market are intended for this type of use so they don’t always adhere well to some metal panels, meaning it could become loose and fall away. Finally, continuous spray foam in this application will not always be able to expand and contract at the same rate that metal does. In some cases, that could mean that the foam suffers from differential movement causing it to break or lose adhesion.

For all of these reasons, be certain to research all options before considering or selecting a foam spray-on insulation that will not negatively impact your roof performance. If a foam insulation is preferred, it may be worth considering the use of insulated metal panels (IMPs) that are designed, engineered, and fabricated to be compatible with metal building construction.

Recognizing all of the above variations and options, the key point to remember about insulating metal buildings is the importance of communication between those designing and ordering an insulated metal building and those who are manufacturing and fabricating it. To find out more about the best ways to do that, contact your local MBCI representative.

Planning for Metal Roofing Retrofits

The decision to retrofit an existing commercial roof with a new metal one is usually based on the very real appeal of creating a long-term (50-60 years) roofing solution, achieving better energy efficiency, creating better aesthetics, or all of the above. Prior blog posts discussed these benefits in more detail and talked about different types of metal roofing retrofits. Here, we will focus on where to start in terms of planning to undertake a roofing retrofit based on covering a membrane roof with a metal-framed, low-slope, metal roofing system.

Existing Building Assessment

A successful retrofit is based on the new metal roof system working with the existing building structure and local conditions. Each of the following should be looked at first when starting the planning and design process:

  • Existing Roof Geometry: The shape (length and width) of an existing roof is important to determine the square footage of the roof, but so are the actual dimensions, since those can impact the height of the new metal roofing. The minimum recommended slope for new roofs is between ¼:12 and 3:12 , depending upon the roof system chosen for the new roof. Existing roof details such as overhangs, parapets, and the existing roof slope itself all need to be documented in order to determine how best to address them with the retrofit system.
  • Existing Roof Type: In many cases, the existing roofing does not need to be removed, but there may be ballast such as stone or other materials that are no longer needed. Oftentimes, the removal of this ballast will compensate for the additional weight of the new roof and framing system. The materials of the existing roof may also pose compatibility issues with new materials, so they should be documented to plan accordingly.
  • Existing Roof Substrate: Under the existing roofing, some type of substrate material is holding it up. It may be rigid insulation resting on a metal, wood, or concrete deck, or it may be an uninsulated substrate that has insulation below it. The specifics here need to be established, since the new metal framing will need to connect through this material. If insulation is in fact part of the substrate, then its effectiveness should be determined—has it gotten wet and been compromised, or is it still in good usable condition? Either way, how much is there?
  • Existing Roof Structure: The structural system of the building includes framing or other components that support the roof. This is what the new metal framing will anchor to and transfer structural loads to. Hence, the specifics in terms of type (steel joists, concrete beams, wood joists, etc.), the size, and the spacing are critical. Further, the carrying capacity of this system should be assessed and analyzed by a structural engineer, since the retrofit system will add 2 to 4 pounds per square foot of dead load to the roof structure. Further, this weight, plus any live loads from the roof, will typically not be distributed uniformly, but in a series of point loads. Therefore, the engineered capacity of the existing structure needs to be known to determine if any structural enhancements are needed.
  • Existing Roof Equipment: Many commercial buildings use the roof to locate mechanical, electrical, or elevator equipment. In some cases, that equipment can be moved to the ground or elsewhere, but in other cases it can’t, or would be too costly to consider. Hence the details, location, and height of such equipment needs to be known so a determination can be made on whether it can be covered and enclosed in the “attic” of the retrofit system, or if it will need to be raised to the top of the new roof.

New Retrofit Roofing Goals

With an assessment of the existing conditions in hand, the focus now becomes identifying the primary objectives of the new roof. These should be clearly articulated so the final design can address and include each of them:

  • Appearance: What is being sought in terms of shape, height, visibility, color, improved curb appeal, or other visual considerations?
  • Performance: What is the new roof being asked to address related to operations or performance issues? Common elements could be improved drainage, less maintenance, greater longevity, or more resistance to damage.
  • Energy Efficiency: Replacing a roof is the ideal time to improve energy efficiency in a building by adding new or more insulation. This could be done simply to meet current energy code requirements or to contribute to an overall energy-use reduction project at the building. In some cases, the new roofing system could enhance the ability to include energy generation, such as solar panels mounted to the new roofing system.

With proper planning and goal setting, a metal retrofit system can meet or exceed all expectations. This was the case recently at a water treatment facility in Dallas, Texas. Here is a photo of the existing built-up roof that was experiencing problems and needed replacement. It was assessed, analyzed and determined to be an excellent candidate for a retrofit metal roofing system.

Retrofits

 

Metal Roofing Retrofits
Here is a photo of the light-gauge metal framing installed to create the new low-slope planes and transfer loading to the existing building structure.

 

Planning for Retrofits
And, finally, here is the completed metal roofing, which looks better and is expected to perform better than the original roofing.

 

To learn more about MBCI retrofit metal roofing systems and how they might work on a building you are involved with, visit http://www.mbci.com/products/retrofit-products/.

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.

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