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Commercial Roof Replacement and the 2018 Energy Code: Cost or Benefit?

Registered Architect, 40 years experience, investigative forensic specialist, engineering trained, college teacher, NCARB mentor, MBA.



So, it has been a while since I have written, and like most things some events have taken place that has given me cause to write this article. Until recently, I have spent the last eight years of my career working for the State of Arizona. My role was as a Staff Architect overseeing facilities. This was the most extensive work in my career in the building owner’s perspective. This had a significant impact on my career as I became more acutely aware of the long-term ramification into materials selection. As a result of that experience, I have developed a very different ideology, evolved if you will, for lack of a better term. As an entity that was required to hold facilities long-term, frequently beyond there expected life, I became amazed at the incredible short-term view taken when it came to building renewal and renovations by many around me. I suppose this is largely a result of the political decision-makers driving these attitudes that hold such short-term perspective at the cost of our entire society. Have quoted Herman Chanen of Chanen Construction with a great statement on this in at least one previous article.

Well over a couple decades ago, I became family with REITs (Real Estate Investment Trust) as I worked extensively in the multi-housing market at that time. Back then, once a REIT invested in a project, that REIT was required to hold interest in that project for a minimum of 10 years. This caused the REIT to have a very different approach to materials selection than your typical real estate investor at that time, which was often focused on a much shorter term. I found myself adapting to that very same long-term view while working for the State. Many of the assets that we oversaw were incredibly aged, well beyond their useful life, yet we had to maintain them because we found resources for replacement of these aged assts was nonexistent. Funding was never available for such replacement. I often found myself leaning towards selection of a material or system that offered a longer life cycle as that was the lowest cost to the taxpayer over the extended life of the system, even in these aged facilities.

Expense Verses Investment

For example, in 19 years of marriage, my wife and I have bought two homes. Thankfully, we used the same real estate agent and at his encouragement, both times, we had a one-year home warranty as part of the initial buy. This was an incredible insight with both homes, as within the first 30 days of buying both homes the water heater failed. Paying a small cost for the water heater so early in the ownership of these large investments, gave us no requirement to replace the water heater again. In our current house (the second home we bought), purchased about five years ago, the new water heater was much more energy efficient and insulated than the old replaced water heater. I will not get into the fact that the water heater is located in the middle of the house and does create an additional cooling load in summer in the A/C unit, but at least it is not as much as extensive as the older water heater would have provided. The unit is so well insulated that we had our gas had been turned off from Tuesday afternoon until Thursday afternoon, and we still had some hot water in the tank by the time the gas was turned back on. This would have never happened 20 years ago with those older units.

I got off on this tangent because I wanted to illustrate how system replacement analysis has to be a complete all facetted approach. Not only the initial cost and the life cycle cost with the system is a consideration, but the impacts on other subsequent systems need to be analyzed. My former Executive Director used the word “tertiary damage” or impact when speaking about these systems. It becomes very easy to relegate these short-term views when we take on the perspective of an “expense”. However, when we are discussing assets that are intended to last 50 or 70 years, the over bearing question becomes, is that the correct assessment? On an asset that has a value of $110 million what is a $1 million roof? Looks kind of like small potatoes to me.

Our political leaders intensify this viewpoint. Why be concerned for long term assets when your time in office is limited to two, four, maybe eight years maximum? This may become the foundation for that short-term perspective on long-term assets. Looking at just inflation alone, using just inflation as a cost decider, the difference in life cycle costs on a 20-year system to a 40-year system is around 320% savings for the longer life system over that expected 40-year period. Maybe this is why we see so much of our nation’s infrastructure deteriorating so much more today. When initial costs become the focus for building renewal, long-term costs are increased, sometimes astronomically.

The Energy Code: Expense or Investment

So, before I get into the Energy Code’s impacts on the commercial roof replacement project, let us explore this thought first. The walls and roof are the two largest heat gain elements in any building. The roof is the one that is replaced more regularly, any where from 10 years to 30 years or more. The walls typically last the lifetime of the building. While at the State, when I had to re-roof a facility, I automatically went to $1 million in my mind. Some were more, others less, but that is where I mostly started. When our Agency received only $50 million plus in funding for almost 150 million square feet, well I am sure you can see this issue. Remember political funding decisionmakers tend to view the budget from a total and then work backwards to the agencies, often neglecting the real needs. So, their tendency is to make the needs, no matter what they are, fit within their monetary constraints. There lies the seed of the problem. If real costs to meet the real needs were discussed, then maybe the discussion would have to change to should the Government really be providing that for particular need?

That is where the pressure comes to cut scope of work no matter what the real needs are. That is why a new building that is expected to have a life of 40 years receives a 10-year roof when it is built. The construction costs would have to be increased a little to provide that 20- or 30-year system, but it would generate a savings over that life period. The focus really needs to be on the view of the cost of future dollars, not just dollars of today. Now comes the energy code, it is known as the International Energy Conservation Code, or the IECC. The current edition of this code is the 2018 publication. As I recall this code was the outcome of some law passed by Congress, I want to say around 1994 or maybe even 1998, somewhere around there, maybe. The law set down goals for energy reduction in buildings and, as I recall, set the baseline for those reductions somewhere around 2000 energy consumption levels. I believe the law set a certain percentage reduction by the year 2025, or something close to that. However, those details are not as important as the result, being the IECC which is adopted across the Country.

Since very early in my career, energy conservation has been very important to me. It is one of the few things I can demonstrate to my clients as a potential revenue generator through savings. It is simple economics and math. As a result, I have always viewed any and all energy conservation methods as a benefit to the project and my client. In some cases, energy savings can become its own profit center. The water heater example is a great reflection of that ideology. I believe that the energy code shares this very same goal. For example, the 2018 Edition of the IECC has a new chapter (Commercial Chapter 5) for existing buildings. At the top of the chapter it has a preface that states, “About this chapter: Many buildings are renovated or altered in numerous ways that could affect the energy use of the building as a whole. Chapter 5 requires the application of certain parts of Chapter 4 in order to maintain, if not improve, the conservation of energy by the renovated or altered building.”

This can be seen as an expense or it can be seen as an investment. My knowledge of business sees an expense as a lost resource, and investment is a resource that gains value. If the additional insulation is placed in a building, then the HVAC system does not have to work as much or as hard, so it’s a savings that the building owner can realize over and over again. Every time the utility bill is paid. How does this not sound like an investment? All this must be taken into consideration when doing an analysis on the long-term costs of additional insulation on any project.

Commercial Roof Replacement

It must be said that all the previously discussed material is part of the determinations of the impacts of additional insulation on any project, but we must now turn to the energy code itself. What exactly does the energy code require? When I first started my career, the building code had a “ratcheted” approach for building code compliance on renovated or altered buildings. If the cost of the work was a very small percentage as related to the value of the entire building, then only the work being done had to comply with the building code. If the percentage was larger, then the entire building would have been required to comply with the code. This became very costly, so it became an issue. Not long after I began my career this language started to be phased out of the building codes. Now only work completed is required to be compliant with the building code, except when we speak of the NFPA 5000 code, which still holds to the “ratcheted” approach, the last I heard. Now the codes address existing buildings within their respective texts.

Now to move onto the topic at hand. The requirements on a commercial building roof replacement with respect to the 2018 IECC. The IECC is a code that many professionals are not as familiar with as it did not exist until the first editions of the ICC (International Code Council) codes in 2000. Most professionals were not even familiar with the proceeding codes of the IECC, for instance the MEC (Model Energy Code). Now professionals everywhere are having to become more familiar and knowledgeable with the IECC, compounded by the fact that the code is a little different in allowing multiple methods and tradeoffs. So, what exactly are the requirements for a commercial roof replacement as found in the IECC?

When discussing the insulation requirements for a commercial roof replacement project on an existing building, the first place to look is in the Existing Buildings chapter, Chapter 5, of the 2018 IECC (International Energy Conservation Code). This is a new chapter in the 2018 edition of the IECC, as this particular chapter on existing buildings did not exist in previous editions of the IECC. Please note that the intent of Chapter 5 is to apply certain parts of Chapter 4 along with the new Chapter 5 requirements, “in order to maintain, if not improve, the conservation of energy by the renovated or altered building.” This is the clearly stated basis for Chapter 5 of the IECC as stated by the ICC (International Code Council) in the chapter’s preface. Much of these requirements have been in previous editions of the IECC, however inclusion of the existing buildings chapter makes these requirements both clearer and easier to locate within the IECC.

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To begin, the requirements for commercial roof replacement is specifically addressed in Section C503.3.1. That particular section states that “Roof replacements shall comply with Section C402.1.3, C402.1.4, C402.1.5, or C407 where the existing roof assembly is part of the building thermal envelope and contains insulation entirely above the roof deck.” Note: This is a determination that must be made by the Design Professional (Registrant) as the IECC requires a complete thermal barrier to be located entirely through one of three prescribed approaches; entirely above the roof deck, below the attic space, or within a metal building, as exhibited in Tables 402.1.3 and 402.1.4. A broken or non-continuous existing thermal barrier regardless of approach utilized is a non-compliant system in a building renovation or alteration by the IECC once the roof is replaced. Court interpretation of this is not readily available, but most other interpretations tend to lean towards the direction that a roof replacement project requires complete insulation above the deck in order to conform to this section of the code. The other approaches may not be able to be completely verify that the existing thermal barrier is complete and totally uniform throughout the existing structure.

Chapter 4 of the IECC concerns itself with Commercial Energy Efficiency, with Section 402 covering the building thermal envelope specifically. Section C402.2.1 exclusively addresses the roof assembly, and that section will be reviewed in a moment. As noted in Section 503.3.1, specific sections referenced are C402.1.3, C402.1.4, C402.1.5, and C407. Section C402.1.3 is based on the component R-value-based method, and references Table C402.1.3. This section is focused solely on the thermal resistive value (R-value) of the insulation for the roof. Section C402.1.4 is the is the U-factor, C-factor, or F-factor method, and references Table 402.1.4. This section is focused on the thermal characteristics of the entire roof assembly as a composite unit. This can be demonstrated as the U-factor for the complete roof assembly is the reciprocal of the sum of the R-values for each assembly component. Section C402.1.5 is the performance alternative and requires the multiple commissioning reports of Section C407. This section looks at the performance of the entire assembly and usually requires extensive testing to prove its functionality, uniformity, and reduction in energy consumption. Any one of these three methods are required by the IECC, which is left to the discretion of the Design Professional analyzing the building. Both cited tables require the climate zone for the project to be identified, and the climate zones are defined in Table 301.1 of the IECC.

There are additional prescriptive requirements for roofing assemblies found in Section C402.2, more specifically Section C402.2.1, which requires the roof assembly to comply with Table 402.1.3, adding that, “The minimum thermal resistance (R-value) of the insulating material installed either between the roof framing or continuously on the roof assembly shall be as specified in Table C402.1.3, based on construction materials used in the roof assembly.” This appears to suggest that the three approaches are independent of one another, in other words they are not to be mixed, e.g. R-20 insulation in the ceiling and R-18 above the deck to equal the R-38 minimum of the below that deck insulation. It can be claimed that this section is written exclusively for new construction and does not apply to the renovated or altered building. This becomes lees of a point of contention as C503.3.1 specifically addresses the commercial roof replacement on renovated or altered buildings.

The section continues by also stating, “Insulation installed on a suspended ceiling having removable ceiling tiles shall not be considered as part of the minimum thermal resistance of the roof insulation.” The IECC considers all insulation installed on the topside of lay-in acoustical grid ceiling tile system as not countable toward the thermal barrier requirements of the Section and the Tables of 402.

To help understand the approaches, one of the most common interpretations for the under deck (noted as “attic and other” in both tables) would be similar to the following detail (taken out of the Building Energy Codes Program presentation by the U.S. Department of Energy, slide 43). This would also apply if the insulation is attached to the underside of the roof deck, as that configuration is used to remove other code requirements for an unventilated attic space within the building.


For metal buildings, thermal blocks are required as indicated in the following detail (taken from same presentation cited as above, slide 40).



To begin, the very premise of the 2018 IECC, with respect to the commercial roof replacement, is to ensure that the energy conservation qualities of the existing building is not diminished at all, and this is a clearly stated goal by the ICC. All interpretations of the IECC must be taken within that parameter primarily, if not exclusively. Also, to be recognized with this is, that much, if not all, application of the IECC with respect to commercial roof replacement, requires the exercise of professional judgement, which by the BTR (Arizona Board of Technical Registration) constitutes the practice of the profession and requires that judgement to be sealed, basically barring a non-sealing / non-Registrant entity from usurping the exclusive judgement of the sealing Registrant.

Section 503.3.1 requires the commercial roof replacement to comply with the above deck insulation requirements of the IECC, as it specifically states, “Roof replacements shall comply with Section C402.1.3, C402.1.4, C402.1.5, or C407 where the existing roof assembly is part of the building thermal envelope and contains insulation entirely above the roof deck.” This direction is clear as Section C503.3.1 requires roof replacements to comply with Sections C402.1.3, C402.1.4, C402.1.5, or C407, “and contains insulation entirely above the roof deck.”

The potential interpretation for this code could conclude that the commercial roof replacement would be compelled to comply with the above deck insulation values of Table C402.1.3 and Table C402.1.4, thereby enhancing the thermal barrier (the stated goal of the IECC). This is a result of the literal interpretation of the word AND in C503.3.1 as a conjunction. This interpretation would require the conjunction to join two separate requirements. The first being, “the existing roof assembly is part of the building thermal envelope”. The second being, “contains insulation entirely above the roof deck.” Thereby being conjoined by the conjunction “and”. This would be a literal interpretation based on the conjunction “and” meaning both parts must be complied with simultaneously.

However, another interpretation for this code could include the concept that as long as the value of existing thermal barrier is maintained, nothing additional more is needed for compliance. This would stay within the parameters of the Chapter 5 preface of “maintaining” the existing building’s energy efficiencies. For instance, the existing thermal barrier is intended to be a functioning R-30 value batt insulation above the ceiling that is supplemented by above deck insulation of R-3 as it was originally installed. Now since this was the existing construction built prior to the 2018 IECC, it could be understood to mean that the roof replacement would only have to comply with this configuration. There are multiple issues with this interpretation. To start, it totally ignores the compulsion in C503.3.1 where the word “shall” is used. Used in this context the word “shall” is a compulsory term that does not allow substitution or option. There are other potential ramifications to this interpretation. This existing configuration might be possible to maintain, if the existing insulation is left in its entirety. However, if the existing roof insulation must be removed, even in part, then the replacement insulation would be required to comply with C503.3.1 and this might create issues where the existing / new insulation adjoin, i.e. height, slope, etc. Another possible issue would be, what if all the existing insulation cannot be seen, identified, or verified, then suspicion must be raised as to its integrity for the entire existing thermal barrier. Now it becomes imperative to quantify and qualify these areas then augment the roof replacement insulation to ensure that the overall R-value does not decrease from the existing conditions. This may become problematic, because what if not all areas are accessible for inspection and verification of the existing insulation’s condition and R-value. Furthermore, how does this interpretation hold solid if insulation has been degraded from service life or previous damage? Is the “existing” thermal barrier value the original initial value R-30 or is it actually the current R-28 from the deteriorated condition from its service life? Due to such issues, this interpretation becomes tenuous at best, especially when ignoring the compulsion “shall” in viewed in C503.3.1.

The conclusion seems to be clear that the grammatical structure of C503.3.1, written specifically for existing building renovations and alterations, requires any commercial roof replacement project to include compliance with the above deck insulation requirements of Table C402.1.3 or C402.1.4. It must also be noted that this increase in insulation will have a slight increase on all commercial roof replacement projects, as acknowledged by the State of Florida. It appears almost impossible to argue that the commercial roof replacement is exempt from compliance with the thermal envelope requirements of the IECC.

Closing Thoughts

While it appears clear to this author that the intent of the IECC requires the commercial roof replacement to conform with the requirements of the code. It is largely left up to the Registrant to make the determination as to which method is the best to use, C402.1.3, C402.1.4, or C402.1.5. However, the use of the conjunction “and” seems to place a prominence on the continuous insulation (CI) barrier above deck insulation approach. Even if this is not the case, the benefit gained by the HVAC system working less looks like it may tip the scales to favor this method anyway. Think about this, if the HVAC is working less, it is saving energy and wear and tear, which will help those HVAC systems have a longer life. These must all be factored into the long-term cost analysis as well.

Maybe this is the best reason for us to start to think more long-term when we look at basic infrastructure needs as a society wholly.

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