Code Requirements for Cool Roofs with Climate Zone Specifics

There is still a lot of discussion—some agreeable and some not so agreeable—about the necessary color of our rooftops.  One side of the discussion revolves around keeping the surfaces of our built environment “cool,” so there’s a movement to make all rooftops “cool” by making them white, or at least light-colored.  Those on the other side of the discussion claim that cool roofs are necessary to reduce a building’s energy use.  Cool roofs can be a really good idea, but let’s not mix up the reasons why cool roofs matter—are we cooling the urban areas (that is, reducing urban heat islands), or are we saving energy costs for individual buildings? Cool Roofs
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The average building height in the United States is less than two stories, but “white roofs” are mostly desired in dense, urban areas…and how many buildings here are less than two stories?  Tall buildings are typically found in dense, urban areas, with shorter buildings dominating the fringe urban areas.  In the suburbs and rural areas, one- and two-story buildings are more the norm.  So we have a mix of building heights in the United States, but the conflict is that the “cool roof” focus is often where the tallest buildings exist.

And unfortunately, a cool roof on a 20-story building isn’t going to reduce its energy use, especially if the code-required amount of insulation exists on that roof.  Rather, reducing energy use of a 20-story building hinges on the energy efficiency of the 20-story-tall walls—R-value of walls, percentage of windows, and solar blocking eaves, just to name a few items.  Conversely, the energy efficiency of a one-story big-box store comes down to its roof.  And for these buildings, roof color definitely can make a difference.  However, our building codes don’t differentiate based on building proportions, but only on geographic location—and that’s problematic.  But as designers, we can improve on the code requirements.

The 2015 International Energy Conservation Code provides specific information about cool roofs, which are required to be installed in Climate Zones 1, 2, and 3 on low-slope roofs (<2:12) directly above cooled conditioned spaces.  There are two ways to prescriptively comply with this requirement: use roofs that have a 3-year-aged solar reflectance of 0.55 and a 3-year-aged emittance of 0.75.   Notice that initial (i.e., new) reflectance and emittance are not specified; long-term values are more important.  The second method to comply is to have a 3-year aged solar reflectance index (SRI) of 64.  SRI is a calculated value based on reflectivity and emittance.  It’s important to understand why a cool roof is desired and to make appropriate design decisions.

To locate metal roof products that meet the IECC requirements, go to http://coolroofs.org/products/results and use the search function to narrow your results or view our finishes’ SRI ratings on our Cool Metal Roofing page.

Reroofing and the Building Code

Reroofing is and always will be the predominant project type in the roofing industry.  Roughly 70-90% of all roofing projects (depending on the year) are performed on existing buildings.  Understanding the reroofing requirements in the building code is critical to proper design and construction.  And fortunately, the reroofing requirements are not all that complicated.International Building Code

The 2015 International Building Code, Section 1511, Reroofing provides the building code requirements when reroofing.  Reroofing projects are divided into two types: recovering and replacement (which includes full removal of the existing roof).

Metal panel reroofing projects must meet the same fire, wind, and impact requirements for roof systems for new construction; however, they do not need to meet the minimum slope requirements (¼:12 for standing seam; ½:12 for lapped, nonsoldered and sealed seams; 3:12 for lapped, nonsoldered, non-sealed seams) if there is positive drainage.  Also, reroofing projects do not need to meet the secondary drainage requirements (i.e., installation of emergency overflow systems is not required).

The requirements for metal panel and metal shingle roof coverings are in Section 1507.4, Metal roof panels and Section 1507.5, Metal roof shingles of the 2015 IBC.  These apply for new construction and reroofing, and include information about decks, deck slope, materials, attachment, underlayment and high wind, ice barriers, and flashing.  The 2012 IBC has the same requirements; the 2015 IBC added new language about deck slope and attachment requirements for metal roof panels.  Nothing was changed for metal roof shingles.

In general, recovering is only allowed if there is one existing roof in place, except if a recover metal panel roof system transmits loads directly to the structural system (bypassing the existing roof system).  This provides a great advantage for metal panel roofs!  The existing roofs do not need to be removed, but new supports need to be attached through the existing roof (typically a metal panel roof) directly into existing purlins.

If metal panels or metal shingles are installed over a wood shake roof, creating a combustible concealed space, a layer of gypsum, mineral fiber, glass fiber, or other approved material is required to be installed between the wood roof and the recover metal roof system.

Good roofing practice is codified in the reroofing section of the IBC; contractors who design and install a recover or replacement metal roof are legally required to follow locally adopted code requirements.  And, of course, all metal roofs must be installed according to the manufacturer’s approved instructions.

Air Barriers and Vapor Retarders

Air Barrier Vapor Retarders

Building design and code requirements are readily becoming rooted in building science, which is the study of heat, air, and moisture movement across the building envelope.

Reducing the heat energy transfer (which is bi-directional based on geography and climate) is why insulation is used.  And arguably more important is the need to reduce airflow (aka, air leakage) across and through building envelopes.  This airflow often includes a lot of heat and moisture; therefore, buildings’ HVAC systems work hard (and use energy…and cost money) to make up for the heat and moisture gains and losses in order to maintain proper interior temperature and humidity levels.  Environmental Building News, in an article titled The Hidden Science of High-Performance Building Assemblies (Nov. 2012) , stated “Air infiltration and exfiltration make up 25%-40% of total heat loss in a building in a cold climate and 10%-15% of total heat gain in a hot climate.”  This is why the model codes are now mandating air barriers.

The 2012 International Energy Conservation Code (IECC), Section C402.4, Air leakage (Mandatory) provides the requirements for air barriers in new construction.  Prior to 2012, building codes did not include air barrier requirements.  The first step taken in the IECC was to mandate air barriers in Climate zones 4, 5, 6, 7, and 8 (locations north of the Mason-Dixon Line, in a broad sense).  Climate zones 4 through 8 are heating climates, where the largest potential for heat loss occurs.   The IECC provides three ways to comply; air barriers requirements can be met through material, assembly, or whole building testing.  A blower door test, used to test a whole building, seems to be the most common way used to show code compliance currently.  The IECC included a list of materials that prescriptively meet the code requirements for air barrier materials; sheet steel and aluminum are on that list.

Three years later the 2015 IECC went a step further.  Section C402.5, Air leakage—thermal envelope (Mandatory) extended the requirement for air barriers by mandating their use in all climate zones in the United States except zone 2B, which is a hot/dry zone.  Climate zone 2-dry includes only southwest Arizona, southwest Texas, and a small part of Southern California.  Essentially all new buildings in the United States are required to have air barriers, and sheet steel and aluminum remain prescriptive air barriers.  It’s important to know that when reroofing, the air barrier requirements do not apply.

The IECC is available for purchase on ICC’s website:  www.iccsafe.org.

Part II – Transparency in Building Products

Transparency in Building Products

A huge buzzword in the building products industry these days is transparency.  The green building movement, which has previously focused on high-performing buildings with a strong emphasis on energy efficiency and fossil fuel use reduction, has increasingly put its cross hairs on occupant exposure risk in the last few years.  Although that change alone is probably enough to start some controversy, how this new emphasis is being implemented is really fueling the fire for new arguments.  If you read our last blog, Part I – The importance of consensus in building standards,  then you should be familiar with how building codes are developed in a consensus-based forum in which all affected parties have some say.  However, many of the movers and shakers of the green building movement have bypassed that forum by folding the requirements they want to emphasize into voluntary programs of their own creation.  At the same time, they lobby owners and building officials to carry some level of compliance to these programs, offering a benefit of being able to say their buildings or communities are “green” by displaying plaques on the façade or being listed on a website.

Although that tact seems fair on the surface, it really puts a lot of power into the hands of self-proclaimed experts to decide on the definition of “green” they want to use for their program. As we discussed in Part I, the ANSI consensus process requires policy-making organizations to transparently prove their competence in subjects they affect with their policy.  Furthermore, they also have to publicly announce the formation of a committee (called a “Call for Committee”) they designate to create and maintain this policy.  They must also allow members of the public to submit curricula vitae for consideration to join the committee without necessarily being a member of the organization.  This introduces a mechanism to balance the power the committee is usurping by having control of the policy going forward.  Unfortunately, no such mechanism exists for many of the authors of voluntary green building programs and the negative aspects of this are particularly pronounced in the area of building product transparency.

One of the most common ways green building programs administer transparency is through the use of a “red list,” which is essentially a list of banned substances.  Using California Proposition 65 or Europe’s RoHS as a model, many of the NGO-based programs related to buildings have some type of requirement that aims to reduce or eliminate the use of ingredients that could possibly be harmful to building occupants.  In many instances, these same NGOs offer third-party listing programs that a building manufacturer can join and have their products declared as meeting the requirements.  Many people see this as a conflict of interest since an NGO, typically funded through donations, is in a position to act as a gatekeeper, allowing in only those companies or industries that support the NGO financially or align themselves with the NGO’s agenda.

But there is a deeper, more disturbing aspect:  Although the list itself may start out as a publicly accepted and scientifically based enumeration of toxic ingredients, NGOs often add other substances that are not known, or in some cases, even suspected, to be toxic in order to dissuade architects from specifying certain products or deploying certain construction methods.  Quite often, the NGO will develop the red list in closed discussion forums where manufacturers have no ability to provide evidence to substantiate that their products are indeed safe.  At best, a manufacturer can ask the NGO to consider exceptions or modifications.  But ultimately, a manufacturer has no assurance that their case has been adequately considered because they are not allowed to attend the forum.  Sadly, this is what passes for transparency in green construction more often than not lately.

This lack of due process came to a head in 2013, when members of congress began to express concern that LEED, the green building program used by the military and the General Services Administration, was not an ANSI-based standard.  In response, the GSA formally announced that they would take public comment on the subject and decided nine months later that they would continue to specify LEED but other ANSI-based programs would be considered going forward as well.  Meanwhile, the military announced that they were developing their own standard, distancing themselves from LEED.  This quelled the discussion for a while and allowed other, even hotter subjects like healthcare to take the spotlight.  But concern lives on that the lack of transparency in the development of LEED and similar programs is leading the public down a dangerous, politics-as-usual road.

However, the news is not all bad.  There are several organizations that use an ANSI-based process to develop and maintain their programs so that the requirements can readily be incorporated into public policy.  ASHRAE, ICC, and a newcomer in the U.S., The Green Building Initiative, have all invested the tremendous amount of time and effort it takes to develop their standards in an ANSI-based public forum, and their respective programs offer a building owner or code official a great alternative to vague voluntary programs subject to interpretation by self-proclaimed experts.  We will explore several of those options in our next blog.

Part 1 – The Importance of Consensus in Building Standards

Building Code Standards BlogMost people understand the purpose of a building code: To ensure the safety of the occupants and to establish the minimum accepted performance level of the building and its systems.  Fewer people understand that because building codes are adopted into law by a governing body, technically referred to as an Authority Having Jurisdiction or AHJ, they are an in fact an extension of the law or ordinance that brings them into effect.  Knowing that, you should not be surprised to learn that like laws, building codes in America can’t just be arbitrarily made up by somebody having the authority and know-how to do so.  Instead, they must have gone through some type of consensus process in which all affected entities or their representatives have the opportunity to participate. This concept, called Due Process of Law, is central to many governmental charters such as the Magna Carta and The Constitution of the United States of America and is designed to ensure that a person’s individual rights are not unfairly taken away.

Under the US Constitution, laws are written by Congress and interpreted by judges.  Members of Congress are elected by their constituents and judges are either appointed by elected officials or elected themselves.  Similarly, building codes are written by consensus bodies, like the International Code Council or ICC, and interpreted by Building Officials, who are generally appointed by elected officials.  The code development process used by ICC is one where any interested member of the public can participate and is guaranteed a forum to propose changes and comment on the proposed changes submitted by others using a system governed by Roberts Rules of Order.  After discussion and debate, the code committee votes on the individual proposals and those that pass are incorporated into the code, guaranteeing due process.  (Actually, it’s quite a bit more complicated than this but for purposes of this blog, let’s just leave it at that.)

However, building codes commonly do not actually spell out all of the requirements for buildings and building systems.  More and more, the code will delegate low-level detailed requirements to a different type of document called a standard, and then brings the requirements contained within by referencing the standard in the code by name.  Likewise, these standards then must also be developed through a consensus process administered by an adequate standard development body.  But because all standard development bodies are structured a little differently, it is not realistic to mandate that consensus process directly.  Instead, another independent body called The American National Standards Institute or ANSI, certifies standard development bodies as having a sufficient consensus processes to be deemed as meeting the incorporating code requirements for due process.  Examples of these bodies are the American Society of Civil Engineers (ASCE) who develop ASCE 7, the document that determines the minimum load requirements for buildings; the American Society of Testing and Materials (ASTM) a group widely known for developing material and testing specifications for general use; and the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), who develops ASHRAE 90.1, the document that spells out the minimum building energy efficiency requirements.  If you are an architect or engineer, all of these acronyms should sound very familiar to you.

Another acronym that you are probably familiar with is LEED, which stands for Leadership in Energy and Environmental Design.  It is developed and maintained by the US Green Building Council (USGBC) and is the premier green building program in the world.  Interestingly though, the development landscape changes drastically when it comes to green construction programs like LEED.  You see, the USGBC is not an ANSI accredited standard developer and thus LEED is not an actual official standard, hence the use of the word “program”.  How then is it possible that USGBC can have so much say in how buildings, particularly publicly owned buildings, get built?  The answer is that they get around this limitation by structuring LEED as a voluntary program and then lobbying the potential owners of buildings, like the US and state governments, into using their program by executive order rather than legislating the requirement directly.  If you’ve watched TV at all in the last year, particularly with respect to immigration reform, you know how controversial this approach can be.  Nevertheless, it is perfectly legal in this context.

This really has not been a significant issue to date because LEED does have a consensus process (albeit not an ANSI accredited one) and LEED credit requirements have been fairly uncontroversial in past versions.  However, LEED v4, the latest generation of the wildly popular green building program, changed all of that by adding credits that are less about design and functionality of the building and more about transparency with respect to building product ingredients to ensure occupant health and comfort.  Let’s be clear: Most reasonable people, including building product manufacturers, don’t have a problem with increased transparency and want more occupant comfort and health.  But it is how LEED defines “transparency” in version 4 has many people up in arms and they point to the hypocrisy of developing a definition to the word “transparency” during a closed-door meeting with no manufacturers at the table as what is wrong with green building as it exists today.  My next blog will explore that concept further.

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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