The art of properly specifying snow retention systems

The recent arctic blasts that hit the northeast brought to mind many things: hot cocoa, the evils of shoveling snow, a nice fire, the longing for a warm beach and, of course, how to properly specify snow retention systems on standing seam roofs. I’m not alone here, right?

All jokes aside, when I was scratching my brain for a new blog post, the cold weather and blizzards reminded me how easy it is to specify snow retention devices improperly. It might appear rather elementary at first; you might think it is as simple as planning for snow retention around entrances and frequent walkways. If so, you, along with many others, are mistaken. Let’s review some not-so-obvious areas to consider while planning a snow retention system for a SSR.

Gutters If a gutter is used that has a face high than the pan of the roof panels, the gutter must be protected from sliding ice and snow. Gutters are designed for one purpose – to channel the water to a downspout. If it is left unprotected it cannot resist sliding ice and snow.

Pipe penetrations As ice and snow slides down a roof and encounters a pipe penetration, the force can cause the pipe to move down slope and damage the roof jack and the roof, or shear the pipe at the roof surface.

Upper roofs draining into lower roofs The upper roof should have a snow retention system installed to prevent ice and snow from falling onto the roof below. Without snow retention, the sliding ice and snow can cause extensive damage to the roof membrane and to equipment on the lower roof.

Panel seams perpendicular to the main roof slope Connector roofs or dormers are typical examples of this type of roof area. The main roof slope provides a surface for ice and snow to slide toward the eave. If it then encounters a roof surface that is perpendicular to this main slope, damage to the roof panels and trim on these roof areas can occur.

Valleys in high snow load areas Valleys allow for snow to slide down a surface that is perpendicular to the panel seams. This offers the potential to bend panel seams down or shear them from the panel.

Aside from considering these areas while planning your snow retention system, also use clamps instead of screws to attach the system to the standing seams of the roof panels. Screws not only perforate roof panels but can also pin the roof and prevent it from floating as designed. Clamps, by comparison, have been tested and can be engineered for the specific roof to which they will be attached, allowing for the snow load, roof slope, panel run length and other details. These clamps do not penetrate the roof membrane, do not hinder roof expansion and are easily installed with a screw gun.

Lastly, I recommend having a registered, professional engineer design a retention system that meets the specified snow loads for the project. Without their expertise there are possible repercussions. If the snow retention system cannot support the snow load, it can result in an entire system failure and major roof damage. This could potentially cause snow and ice to fall and hurt bystanders.

By keeping all of these in mind, along with proper installation and maintenance, a snow retention system will help your SSR survive winter blasts and protect pedestrians, too.

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Standing the test of time: new study reveals 55% Al-Zn alloy coated standing seam roofs last 60 years

The majority knows that metal roofs are durable, but it wasn’t until recently that a study showed the longevity of low-slope unpainted 55% Al-Zn alloy coated steel standing seam roofing (SSR) systems- 60 years. With the service life of a commercial building being 60 years, according to LEED version 4, this means that essentially the metal roof system described above, and commonly referred to as Galvalume® metal roofs, does not require replacement. To put this into context, by comparison most non-metal roofs require at least one replacement during the same period. This study also reveals that the longevity of a 55% Al-Zn alloy coated standing seam roofing system far surpasses the typical warranty period granted, which is 25 years. Basically, this is a game changer and we, manufacturers, are thrilled!

Technical Director of MCA Scott Kriner said, “This study is a breakthrough for the metal construction industry because it finally provides third-party, scientific data that backs up the long held stance that 55% Al-Zn coated steel standing seam roofing systems are very durable, economic and can be better for the environment.”

Let’s take a closer look at the study. The Metal Construction Association (MCA) and Zinc Aluminum Coaters (ZAC) Association sponsored it. The study involved three independent consulting firms testing 14 buildings in five climate zones. The variety of structures and climates allowed them to analyze how Galvalume metal roofs perform in a range of temperatures, humidity and precipitation pH, or acidity, levels. All of these can affect the metallic corrosion rate of roof panels, their sealants and components, and that’s what the consulting firms analyzed.

Here were some of their findings:

  • First, the sealant life is the primary deciding factor in establishing end-of-life for Galvalume metal roof systems. In certain structures analyzed that were 35 years old, the sealant was considered “entirely adequate and without issue.” Based on the sealant performance, the study conservatively projected the lifespan of such roof systems to be 60 years.
  • Secondly, although a Galvalume metal roof is moderately maintenance-free, all roof systems require a periodic inspections and maintenance in order to achieve such long lifespans.
  • Thirdly, while the roof system as a whole was projected to last up to 60 years, components may need to be replaced during this period. The cost of replacing components, however, is considerably less than 20% of replacing an entire roofing system, which is the value deemed by this study as excessive to the point of constituting the end of service life for a roof system.
  • Lastly, the study unveiled that even on areas typically most susceptible to corrosion, such as panel profile bends, there was an absence of significant rust after 35 years; even at its most vulnerable areas, a Galvalume metal roof system performs well.

So what does it mean for architects and building owners? Speaking from a purely biased manufacturer’s prospective, specify and purchase more metal roofs! All jokes aside, this study displays the appeal in selecting a metal roof because it reduces the maintenance costs of the building. It also changes and increases the accuracy of Life Cycle Cost (LCC) or whole building Life Cycle Assessment (LCA) associated with Galvalume metal roof systems by providing tangible research as opposed to previous calculations based on roofing professionals’ opinions. To find out more information or to download the full report, visit

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A difference in terms

It is an industry standard that we use the word “gauge” to describe the thickness of steel coils and sheets. Metal panels rolled from coil come in a range of gauges, with many of our panels’ standard being 24 gauge. This format is based on the Manufacturer’s Standard Gauge (MSG) which is a remnant of an outdated standard.  It’s not until you take a closer look do you realize that specific gauges, such as 24, can equal a range of thicknesses.

When steel coils were rolled decades ago, manufacturers lacked the technology to consistently produce material thicknesses to the tolerances regularly achieved today. Therefore, a relatively large tolerance range was established for the MSG system and this tolerance determines what range of thicknesses qualifies as a particular gauge. For example, as you can see in the table below, 24-gauge panels can range from 0.0269-0.0209 inches.

As time went by and technology improved, coil manufacturers could produce material down to the thousandth of an inch of thickness, and the MSG system was considered outdated by many in the industry. Instead, the Standard Decimal System was introduced. This system defines gauges by specific minimum thickness expressed in decimal numbers instead of a range, eliminating the tolerance. Although widely accepted throughout the industry, the architectural community has been reluctant to adopt this system when specifying building products.

Because the architectural community is still specifying buildings using the MSG system, manufacturers still list their products by it as well. This leads to some manufacturers taking advantage of the MSG system’s large tolerance and producing panels with the minimal thickness allowed to qualify for that gauge. For 24-gauge panels, for example, they might roll it to 0.0209 inches, instead of the nominal 0.0239 inches. Although still technically allowed it seems misleading to me, especially when you consider other manufacturers who spend more money to achieve the specific gauge advertised true to the intent of the MSG system. In addition, this difference in thickness, even in the thousandths decimal place, leads to a difference in structural performance and strength. This can potentially lead to inaccuracies in architects’ specifications or even worse, under expected performance. That said, I think it’s worth the extra effort to take a closer look before selecting products and that it is the manufacturers’ responsibility to present their products honestly.

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Building in the public eye

Government spending is always under scrutiny. I currently live in a construction zone (prime real estate, I know), and I catch myself judging the new road plan, project timeframe, resting construction workers, etc. This very same principle can be applied to the construction of public buildings. It’s important to be efficient with your costs and timeframe. It wasn’t until I joined the metal panel manufacturing industry that I realized how much they can help contractors and facility owners with both.

DCTATake for instance the Denton County Transit Authority (DCTA) in Denton, Texas. Their operations were expanding so rapidly that they were in need of new facilities to house their growing fleet of buses. As a provider of mass transportation, DCTA was already focused on reducing fuel costs and eliminating carbon dioxide emissions. Rightfully so, they were environmentally conscious and wanted their new facility to reflect the same. To help achieve this sustainability, Huitt-Zollars Architectural Firm selected insulated metal wall panels, single skin metal roof panels and soffit panels.

DCTA’s new facilities consisted of two offices and a maintenance and fueling building and used over 5,000 square feet of metal panels. MBCI supplied 1,300 square feet of eco-FICIENT® Grand H insulated metal wall panels in Stucco White, 1,200 square feet of 7.2 exposed fastening panels in Silver Metallic and 2,500 square feet of FW-120 concealed fastening panels in Snow White.

MBCI’s eco-FICIENT® Grand H insulated metal wall panel provides the durability of metal while its non-CFC foamed-in-place polyurethane core delivers the energy savings of DCTAinsulation. The panel can achieve an R-value up to 8.5 per inch of panel thickness. Additionally, since the panel and insulation are manufactured together and delivered as one piece, it reduces installation time.

The 7.2 Panel and FW-120 concealed fastening panels have been tested by a certified independent laboratory in accordance with ASTM test procedures for Air Infiltration and Water Penetration. The test results show the FW-120 panels have no air leakage at 1.57 PSF and no water penetration through the panel joints at 6.24 PSF differential pressures. The 7.2 Panel’s DCTAtest results show no air leakage at 6.24 PSF and no water penetration at 13.24 PSF.  Furthermore, the symmetrical rib of the 7.2 Panel offers excellent spanning and cantilever capabilities.

Using metal panels increases energy efficiency while reducing energy and maintenance costs, driving a building design’s success and making you and taxpayers happy!

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Metal roofs offer energy-efficiency, durability and recycability

Metal roofing material is known for its durability, but it also offers two other sustainable attributes that are sometimes overlooked: enhanced energy-efficiency and high recyclability.

When coated with a light-colored reflective paint, metal is a superior material for a cool roof. A three-year study on the energy efficiency and service life of metal roofs by Oak Ridge National Laboratory’s Buildings Technology Center found that the high solar reflectivity and emissivity levels of cool metal roofing can greatly mitigate urban heat island effects. The study used a solar spectrum reflectometer and an emission meter to test the efficacy of cool metal roofs.

Oak Ridge found that white coatings on other roofing materials displayed a 25% to 40% drop in their initial reflectance, but the metal roof tested retained 95% of its initial solar reflectance during the length of the study. Depending on the color of a painted metal roof, the reflectance ranges from 10% to 75%, which compares very favorably with the 5%-to-25%-range of an asphalt roof.

Metal is also highly reusable, and metal roofing material rarely ends up in landfills. Many metal roofs contain up to 40% recycled steels. Their material is also 100% recyclable. Research conducted by the Florida Department of Environmental Protection found that metal is one of the best eco-friendly roofing materials from a waste-reduction standpoint.

All in all, metal is among the most sustainable roofing materials, especially when you consider that metal roofs can last more than 60 years.

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“BUILDING” the future of an industry: How collaboration, creativity & ignorance can change the face of the built environment

As the design and construction industry moves forward and we all (product manufacturers, designers, and clients alike) start to seriously consider the ideas of legitimate “differentiation” (among our peers, designs, and products) the ideas of multi-industry collaboration and mass customization come to mind…

CU Denver HOZHO House

Photo courtesy of Rick Sommerfeld

Should we decide to go down this road, there are most definitely very real challenges that await: raw material costs, set-up and tooling charges, time/schedule and testing for starters. Then there’s the seemingly insurmountable challenge of multi-company and multidisciplinary coordination… At company A) “x” means one thing, while at company B) “x” means the exact opposite… How do we ensure that our products/designs/buildings don’t in a sense have two left feet after navigating this process? At the end of the day, however, should we rise to the challenge and navigate these obstacles successfully, the pay-off will be enormous. Below are a few key ways to make this happen.

Secretly, many architectural designers fancy themselves as inventors of sorts (I know that I did/still do). They are often times quite literally creating something out of seemingly thin air in order to correspond with the client’s/owner’s hopes and dreams. The only problem is when you run out of time, money or needed/interesting “building blocks”.

Earlier this year, I was approached by a senior-level principle of a world leading design firm, regarding the possibility of partnering up with MBCI in order to bring new products to market. The basic gist of the conversation was: “We have the design know-how and experience, while you guys [MBCI] have the manufacturing and testing experience. Why not partner up and bring new stuff to the market that no one else ever possibly could?” Why not indeed? Currently that is a topic that is still on the table. It is through conversations like these that true progress is really made, and I am greatly encouraged by the future of this relationship.

In order to move forward we must each take risks, we must look to the future as a real opportunity for change and we must embrace both ignorance and naivety for it is by only not knowing one’s “limitations” and what is (and what is not) currently “possible”, that innovation can occur.

While in graduate school at NC State, I was fortunate enough to have had more than my share of inspirational conversations with some of the world’s finest architectural and design minds, not the least of which was one particular discussion with Michael Rotondi of RoTo Architects. “I look for design inspiration in everyday life, but most importantly from my thirteen year old son and my interns. I’m too set in my ways to ever think about things much differently than I already do, but by keeping an open mind, I am always exposed to a fresh perspective.” How many of us out there are open to such a philosophy? How many of us could benefit from such a strategy? I would be willing to bet nearly everyone (and every industry).

Embrace the enthusiasm of people eager to learn. Architecture/Design School is many things, but it is most assuredly anything but easy. Mental toughness and the ability to solve complex problems quickly are unspoken but very real prerequisites for graduation. Most disciplines have tests with one “right” answer. Design education takes a drastically different approach. There are quite literally countless “right” answers to the same exact problem. If you put one hundred designers in a room and ask them each for a solution to the same exact design problem you will get one hundred different answers. There are legitimate reasons for each of these answers, and throughout their education students are continuously thrust into this situation. Students must not only provide their answer but must also present their solution to a jury of their peers, professors and practitioners. This is their test… This process helps to create the strongest of work ethics (no one ever wants to be embarrassed repeatedly in a room full of their colleagues/friends), the ability to take constructive (and sometimes unconstructive) criticism, the ability to think on their feet (you can never know what they’ll ask or focus on), as well as the ability to not only come up with creative solutions but also to SELL them. Any company looking to innovate can benefit tremendously from their share of employees with this background and experience. Why not start that process earlier with direct relationships with the schools/students themselves? I challenge any company or industry to consider this approach. I can promise you that you will see tremendous results.

I am very proud of MBCI’s commitment to this ideal and to have had the opportunity to have worked with many such students during the past year. I am even more proud of MBCI’s contributions of both time and materials to two design-build studios (North Carolina State and CU Denver) this past summer as both of those projects are not only beautiful, but also support great causes (see links below). As great as these two particular projects are, I am hopeful that that they are only the beginning and that we will continue to seek out and respond to similar opportunities in the future.

North Carolina State University: Floating Lab project for Durham Public Schools
About Durham Public Schools HUB Farm:

University of Colorado Denver: HOZHO House, DesignBuildBLUFF
About DesignBuildBLUFF:

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Gold Medal for Metal Stadiums

We’re a little less than two weeks away from the 2014 Winter Olympic Games, and I must admit, I’ve caught a bit of Olympic fever. I’m getting updates on my phone, I’ve got my DVR set to record my favorite events, and I have a countdown to the opening ceremony running on my desktop. (As of this post, we have 10 days, 1 hour, 39 minutes, and 40 seconds to go!)

Sochi Stadium, courtesy of

Aside from the Olympic events and the incredible athletic prowess displayed by the competitors, one of my favorite parts of the Olympics is the stadium, or stadiums, since the Games usually require multiple. Most host cities end up building additional stadiums and venues, and they have yet to disappoint. They’re always beautiful architectural achievements, works of art really. From the first Olympics in Athens to Games within the last decade, the stadiums steal the show, for me anyway.

We’ve got our share of beautiful Olympic stadiums here in the States, too. The Weber County Ice Sheet in Ogden, Utah was constructed for the 2002 Salt Lake City Winter Games. It served as a venue for curling matches, and since Ogden is only about half an hour outside Salt Lake City, it was an effective answer to the question of stadium space. The Ice Sheet continues to be an immense asset to the town of Ogden and has even had a Sports Complex added to it, serving as an athletic facility for both Weber County and the local college, Weber State University.

The Weber County Sports Complex
Ogden, Utah

The Sports Complex addition features nearly 22,000 square feet of MBCI’s 7.2 Panel, an exposed fastening roof and wall panel, and 3,000 square feet of flat sheet panels. The combination of these panels achieves a sleek, industrial presentation – perfect for an athletic center. The color selected for both the 7.2 Panels and the flat sheets is Silver Metallic, further adding to the building’s streamlined appearance.

Whether they’re in Athens, Salt Lake City, or Russia, the Olympics are always worth watching. Everyone has that one thing they love about the Olympic Games. It might be the Opening Ceremony, the actual competitions themselves, or if you’re like me, the breathtaking environments in which they all take place. Whatever it may be, we all have one common goal – bringing home the Gold. Good luck, Team USA!

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Radiant Barrier FAQ: Everything you want to know but were afraid to ask because you didn’t want to sound like a nerd

I’ve always been a huge fan of the space program (Shocked to hear that, are you?) and I remember as a kid watching the space shuttle launch and repair satellites and was always curious why everything was wrapped in shiny foil. Now, as an engineer and resident energy nerd for my company, I encounter radiant barriers often. That has closed a loop for me because it turns out the mystery foil on the satellites and equipment was indeed a radiant barrier.

Radiant barriers have been around a long time. They have been used extensively in the space program for decades and even on the Lunar Excursion Module (LEM) used to land on the moon. There are many examples of materials developed for the space program making their way into everyday life and radiant barriers are just that. Incredibly, these materials are cheap and very effective in reducing energy use in a building as well. However, they are also often misunderstood and in order to help that confusion, I recently combined the questions I get about them in a FAQ format and would like to share them with you. So, push up those taped glasses and let’s go!

1.       What is a radiant barrier?

A radiant barrier is a special type of insulation that resists transmission of radiation, typically in the infrared spectrum.

2.       Gee, that’s nice. Now in layperson’s terms, how do they work?

Let’s back up a little. There is a law in thermodynamics that states heat will always travel from a warmer point to a colder point. And when it does, it does do in three possible modes: Conduction, convection, and radiation. Conduction is generally applicable to solids, i.e., a handle of a metal spoon with the other end submerged in hot soup getting warm. Convection is generally applicable to gases and fluids because they can flow, transferring energy from one point to another. Hot air rising up out of a fireplace, heating the flue as it goes is an example of heat transfer by convection. Radiation is heat traveling at light speed in the form of electromagnetic radiation, mostly in the infrared spectrum for objects at Earth surface temperatures. When you put lighter fluid on a fire and it suddenly flares, you will feel a burst of heat on your face instantly, right? That’s radiation.

So if you think about this, you will come to the conclusion that all heat from the sun must get to the Earth through radiation because of the vacuum of space. That is correct and exactly why radiant barriers are so important in the protecting satellites and astronauts from the extreme temperature swings they would be subjected to otherwise. You see, space isn’t really cold because the concept of temperature kind of breaks down in a vacuum. In reality, objects in space can be either very hot or extremely cold depending on their exposure to an energy source like the sun. So when a satellite in orbit goes behind the Earth, its temperature would plummet suddenly without a radiant barrier. That’s also part of why satellites are constantly rotating, to make them warm and cool evenly and prevent premature failure on the instruments on board.

But back to Earth-bound, near-room temperature objects: Most solids are very efficient (about 90%) at converting heat to infrared radiation or vice versa in order to match the temperature of their surroundings. But there are notable exceptions, one of which being polished aluminum, which is much less efficient at converting heat to radiation and vice versa. This means that in a vacuum (i.e., no conduction or radiation can happen) a warm object coated with polished aluminum will cool slower than it would without the coating. Thus, polished aluminum is a key ingredient of a radiant barrier and thus has saved many astronaut lives.

3.       I thought aluminum conducts heat readily but now you’re telling me it is a good insulator?

No, I’m saying it’s a good radiant barrier. Remember, those are different things. Radiant barriers don’t have to be very thick to work, so a common approach is to take a conventional insulation liner and coat it with a thin layer of aluminum. That layer doesn’t have any direct effect on the R-value of the insulation. Now, if you were to touch the radiant barrier with another solid, only then would you have solid-to-solid contact and conduction would be a factor. Fortunately, conductors can only transfer what is transmitted to them, so the insulation still limits the heat loss. But what matters is that the radiant barrier makes the insulation work more effectively when it is placed next to air, either against a cavity or lining a room, by impeding radiation release from the insulation into that adjacent space. Think of a baked potato wrapped in aluminum foil. It will stay hotter than an identical potato without the foil even though aluminum is a good conductor because the foil emits far less radiation than the potato skin, keeping the energy contained in the soon-to-be eaten hotter potato.

4.       I’ve seen that but I’ve always called it reflective insulation.

Many people do. But that name is a bit misleading, kind of like putting a statement in a FAQ. (Really, who would do that?) A radiant barrier doesn’t reflect radiation per se; it just does a bad job absorbing it. But we can leverage that behavior to increase the effectiveness of the insulation it’s attached to just as we do with a baked potato.

5.       How much does a radiant barrier increase the insulation R-value?

R-value is a measure of the resistance to heat flow through traditional insulation and isn’t really applicable to radiant barriers. While it is true that energy is energy whether it is transmitted by radiation or some other mode, the amount of energy impeded by the use of a radiant barrier depends on how it is deployed. The only way to know with much certainty how much heat it is impeding is to test or model every possible configuration and calculate a total heat transfer coefficient, or U-factor for each one. This is obviously not very practical. However, there are some references you can find on the internet that will give “effective R-values” (equal to 1/U-factor) of a radiant barrier deployed in certain common configurations. They work well as long as you read the fine print and don’t use them out of context.

6.       Then how is the effectiveness of a radiant barrier measured?

Radiant barriers can have one active or low-e face and an inactive face but you can also get them with two low-e faces as well. The emittance of the low-e facer is the key number. Remember that the lower the emittance, the better the radiant barrier. The lowest emittance readily available is 0.03. But it is a continuous scale and what really matters is difference between the emittance of the radiant barrier and the other solid objects in the room with which the barrier trades radiation. In fact, any material with lower than average thermal emittance (let’s assume that to be 0.9) will function as a radiant barrier to a certain degree.

If you are using a single-sided radiant barrier, you must be careful to install it in the orientation that will give the best results for your particular climate. Generally, this will be with the low-e side facing the predominately cooler environment, be it indoors or outdoors. If you install one with two low-e sides, then you don’t need to worry about it; winter or summer, it will help you save energy

Aluminum is also commonly alloyed with zinc to make a corrosion-resistant coating called Galvalume. This coating has an emittance around 0.15, so it actually can be used as a radiant barrier as well as a durable coating for a roof or wall panel. MBCI makes virtually any one of its profiles in Galvalume as well as painted colors and they can help you leverage that aspect in your building.

7.       How much money can radiant barriers save?

It depends. Radiant barriers don’t actually result in a significant direct change in room air temperature, because air is mostly transparent to infrared radiation. (I say mostly because naturally occurring greenhouse gasses like carbon dioxide and water vapor do absorb certain frequencies of infrared radiation causing them to warm slightly.) Instead, radiant barriers work by preventing radiation from escaping the interior environment in the winter and keeping it from intruding in the summer. This keeps the solid objects in the room closer to room temperature and they in turn reduce the heating or cooling load indirectly. Take the summer condition as an example. The radiant barrier slows the release of infrared radiation from the exterior heat coming through the insulation. This makes solid objects in the room (like humans) absorb less radiation from those surfaces. At the same time, those same solid objects are releasing their own radiation at the typical 90% efficiency. This results in a net radiation loss to those objects, cooling them even though the air temperature in the room doesn’t change much. The opposite happens in the winter by keeping the radiation released by the solid objects contained in the room. How much energy this saves is going to depend on what is in the room, what its emittance is, etc. The classic residential application of a radiant barrier is on the underside of the roof, adjacent to the attic air space. Because access is easy and radiant barriers are fairly cheap, paybacks in this scenario are usually in the 2-year range or less. That’s a solid investment from an energy-savings standpoint.

Another ideal and easily accessible place to put a double sided radiant barrier is on the inside of a roll-up door. MBCI’s door division, DBCI, can provide radiant barriers for most of their roll-up doors, aiding the energy efficiency of a conditioned warehouse as a prime example.

Insulated Door

So, there you have it: Everything you wanted to know about radiant barriers but were afraid to ask because you didn’t want to sound like a nerd. Fortunately, some of us remain blissfully unaware of our nerdism and are happy to answer your questions.

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The “Fuzz Factor” in Engineering: When Continuous Improvement is Neither

Sometimes, being an engineer makes want to put my finger through my eye, into my brain, and swish it around. Reading and interpreting code requirements is one of those times. I’m not that old (please let me live in bliss on that one) but in my almost 25 year career as an engineer, I have seen some 75 code and standard revision cycles representing thousands of pages of text to review and interpret for laymen who are cursed with having to make a living selling building materials in this brutal marketplace.

I know the purpose of building codes and standards is to protect the public who need protection from the very real threats of hurricanes, tornadoes, earthquakes and freak snow storms. As an engineer who has taken an oath to protect the public, that responsibility is paramount to me and is one I carry with pride, I guarantee it. But the system we have set up to protect society in this regard has grown beyond a manageable state into monster status. Moreover, it is a venue filled with hundreds of hyper-sensitive, over-reacting people with individual research and commercial agendas, ballooning paper and free-running ink. In a recent personally defining moment, I stepped away from the tree trunk pushed firmly against the end of my nose and decided to gander upon the whole forest. What I saw concerns me because of the responsibility I have to protect the public. You see, I’m beginning to believe that the biggest threat to human life in a building is not the possibility of natural disasters but instead the threat of simple human error that increases in probability every time we plant a tree in our precious forest of public duty by introducing a code or standard change proposal. The requirements in these documents are long and complex already and getting them applied correctly to a project in a reasonable amount of time while battling the constant barrage of phone calls, texts, and emails a feat worthy of the likes of Albert Einstein and Carl Fredrich Gauss. (If you’ve never heard of Gauss, I suggest you Google him. He was one of the greatest minds of all time.) It has been called by those who have ventured down this thought path before me as the “Fuzz Factor” and I believe it to be a very real threat to public safety in today’s engineering world.

Let’s start by looking where the rubber meets the road. In 1960, the AISI cold-formed steel specification had 22 pages of requirements. In 2007, it had 114.  The latest edition, 2012, has 150 pages. That’s a 680% increase in 52 years. Congratulations, AISI. You have the smallest growth rate of all the standards I track at a little under two pages a year. Hey, stop laughing at your thin-walled brother, AISC design specification because you should be ashamed. In 1941, you had 19 pages of requirements. Twenty years later, you had 57 pages.  Ten years after that, 157 pages. In the most recent edition, 2010, you’ve ballooned to 239 pages. That’s about 3 pages per year not including the seismic provisions. That little piece of work did not exist until 1992 at 59 pages and is now a fat 335 pages in length. Growth rate: a whopping 15 pages per year. That’s something akin to sumo wrestlers in training. It is no better on the load side of the equation, either. ASCE 7, the standard that establishes the load levels to be expected from environmental phenomena like snow, wind, earthquakes, etc., was 92 pages in the 1988 edition. The latest edition, released in 2010 is a sporty 368 pages. That’s a growth rate of 15 pages per year as well.

Now, let’s look where pencil meets paper. Ultimately, the problem manifests in the fact that people reading and applying the code provisions are human beings with all of the limitations bestowed upon us by our creator(s) or evolution, however you choose to view that. The question is: Have human minds grown in requisite ability to read and understand all of this information? Being that Gauss died in 1855 and there has not been another mathematician like him since then, I’d answer that question with a strong “no” and I’m not alone in that. There are quite a few educational psychologists who buy into the theory that we are actually getting less intelligent as time goes on, even though we are much better educated as a society, because education tends to stifle creative thought at an early age and that skill is not developed.

So, how do we address this trend of growing complexity and shrinking time? In my opinion, the answer is relatively simple. Instead of continuing to further define the problems and solutions like we’ve done so well in the last century, we need to consider evolving the engineering process to match the complexity level thrust upon the practitioners. Buildings don’t fail if the diaphragm resistance was wrong in the second significant digit because there was no torsion considered or because a column had second order effect that magnified its load by an unexpected 10%. Instead, they fail because the resistance was overstated or the load understated on a global level by 50% or more because that’s the level of conservancy in the code typically. Case in point: The 1983 Kansas City Hyatt disaster. The initial design by the engineer was a good one and likely would not have failed. It was a later revision to that design, one that gave it less than half of the capacity of the original, that ultimately caused the disaster. The proposed change came to the engineer at a time that they were busy working on something else and was not given proper consideration. A simple human error that any of us, no matter how smart we might be, are capable of.

To me, today’s environment is one where “can’t see the forest for the trees” problems flourish. Fortunately, those problems are fairly easily spotted when put in front of a person who is capable of seeing the forest because they don’t have an in-depth knowledge of the trees growing in it. In this case, that could be a peer engineer performing a simple cursory review. To make this fully effective, it should not just be one or two peers. It should be more like 5 or 10 people with widely varied experiences and preferably strong cultural diversity, each one spending an hour or so scanning the results of the design, rather than the design itself.  Diversity is more important than you might think because each of us brings to the table a unique set of skills but at the same time, we are all limited to our experiences. It’s the old adage that the oncologist will tend to suspect cancer and the dietitian will tend to cite nutritional problems with the same patient. So, let’s do what doctors do in this situation: Swallow our pride and ask for a consult from a practitioner whose experiences are different from our own. It’s simple, easy, and could save lives, let alone all of the trees consumed by the printing of fat building codes and standards.

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Roof Hugger – A Viable Option for Metal-Over-Metal Retrofits

As most metal roofers know, there are literally billions of square feet of metal roofing in the U.S. nearing the end of its service life.  So, when it’s time to reroof these buildings, what should one do? Should you tear off the old roof and start over or simply remove the fasteners from the existing roof and install another roof over it?

There are a number of issues a roofer will have to deal with when it comes to metal-over-metal retrofits, but listed below are a few where the use of a Roof Hugger system may help resolve:

  • Does the existing roof need an insulation upgrade?
  • Are there workers in the building that would be at risk if the existing roof is completely removed for installation of a new roof?
  • Do current code requirements dictate the addition of closer fastener/clip spacings?

Chances are that roofs installed 40 or 50 years ago did not have much insulation under them. These days, everyone is concerned about heating and cooling costs.  Certainly a better insulated roof would help in the majority of cases. The use of Roof Hugger systems allows you add blanket, rigid and/or reflective insulation between the existing and new roofs.

By using Roof Huggers, the existing roof can be left in place. This provides for a safer environment for both workers inside the building and the roofers as they install the new roof. With the existing roof left in place, there are typically no “leading edge” safety issues. Leaving the existing roof in place will save a substantial amount of labor and eliminate hauling the old roof off.

Current code requirements may dictate that the new roof be able to withstand greater uplift pressures  than was required when the building was originally built, particularly in the edge and corner zones of the roof where the pressures are higher. In some cases, the use of Roof Huggers may increase the existing building’s purlin load capacity by providing additional brace points. When this is not enough, the Roof Hugger system has the ability to provide additional attachment points between the existing purlins.


The use of Roof Huggers also allows a building owner to incorporate technology such as solar thermal into the new cavity between the existing and new roofs. Solar thermal technology, used for preheating water or to help heat the inside of the building, is the most efficient use of solar technology that one can employ.

As you can see from all these benefits, Roof Huggers should be considered for any metal-over-metal retrofit to ensure that your new metal roof performs to its greatest potential.

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