I will probably be accused of beating a dead horse but the horse is not dead yet. I am talking, of course, about the 2010 edition of the International Energy Conservation Code. This code is scheduled for final hearings in June of this year. When it is adopted it will then be up to the states and local jurisdictions to make it law by establishing their own energy code based on the IECC 2010 model code. The local jurisdictions have the ability to make changes to the model code to adapt it to what they perceive best fits the local needs. Currently only a couple of states have an energy code in place. That will change in the very near future, so you will have to be aware of yet another set of requirements that will have an impact on your work.
Here is a little background on how we arrived at this point. Let’s establish up front that I do not have anything against the saving of energy; in fact, I’m all for it. What I am presenting here is the information as I see it and how it will affect our industry. We have all been inundated with information about energy consumption and the waste of energy. One set of figures established that the biggest waste of energy was buildings. Data from the U.S. energy information administration indicate that buildings are responsible for almost half (48 percent) of all energy consumption and GHG (Greenhouse Gas) emissions annually; globally, the percentage is even greater. Also, 76 percent of all power plant-generated electricity is used just to operate buildings. From an energy conservation standpoint that is a very meaty target and one worthy of attacking.
And that is exactly what the Department of Energy did.
In the early 1990s an energy policy was established mandating that a 30 percent reduction in energy consumption be attained by 2015. DOE’s stance to date has been that if the industry does not respond with the tools needed to attain this goal, DOE will produce a federal energy code. The International Code Council responded with the IECC 2010 edition.
One of the proposals up for adoption by the final code hearing is for the opaque exterior envelope of the building. DOE in conjunction with The American Society of Heating, Refrigerating and Air-Conditioning Engineers has revised ASHRAE 90.1 establishing prescriptive standards for the insulation values of a building. Of particular interest to our industry is the concept of continuous insulation. This concept was developed to eliminate potential thermal shorts caused by the framing system. DOE has also taken the stance that the concept is “cladding neutral.” That is to say DOE does not care what the exterior cladding is as long as the continuous thermal value of the wall is maintained. This translates into additional thickness of insulation on the exterior face of the framing. Normally the insulation has been installed in the cavity of the wall.
Of particular interest to AWCI is the effect that this mandate will have on traditional three coat stucco systems on cold formed steel framing systems. These systems currently depend on insulation in the cavity to attain the required thermal design value. While adding additional insulation between the metal lath and the substrate may seem like the easy way out, the question of fastening the lath to the substrate raises serious constructability issues. The framing system supporting the stucco requires a deflection value of L/360, and the system weighs approximately 12 to 15 pounds per square foot. Under normal conditions the lath is attached to the framing members; attaching to the sheathing is not allowed under the requirements of ASTM C1063. This means that longer screws are required to attach the lath. This situation places additional loads on the screws and the question is, Will the screws be able to resist the moment arm created by the by the inclusion of the insulation in the system? This is just one of the questions that needs to be answered.
Another is, What will the addition of insulation to a stucco system do to the fire rated systems now available? Fire rated exterior walls are in common usage in California. In many cases, stucco is the cladding of choice of many owners and developers. The current legacy systems do not include insulation in the system. This is yet another important item that will require investigation to determine its viability.
What is AWCI doing about this? A task group has been formed to investigate the ramifications of the 2010 IECC on traditional three coat stucco systems. The first meeting will be held in Denver during AWCI’s Convention on April 21. We have invited manufacturers and bureaus to give us their input. Chief among these are our members on the West Coast who have already taken steps to determine a course of action. See you in Denver.
Donald E. Smith, CCS, is AWCI’s director of technical services. Send your questions to smith@awci.org or call him directly at (703) 538.1611.
