STEEL FRAMING ALLIANCE | FRAMEWORK ONLINE
  April 7, 2010
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SFA Research Provides Siding Attachment For ‘The 30 Percent Solution’

Most people reading the above headline have probably never heard of the 30% solution, or if they have, then they probably conclude that it does not impact cold-formed steel framing. 

Unfortunately, the 30% solution has major implications for CFS.

The term “30% solution” can be found in several proposed bills before Congress over the past few years. In summary if these proposed bills became law, it would require all future energy codes to be 30% better than codes from the 2004 to 2006 time frame.  This includes the codes developed by the International Code Council (ICC) and the ASHRAE 90.1 energy standard. 

Because ASHRAE 90.1 is adopted in Canada, the proposed legislation has implications outside of the United States. 

Interestingly, the specific legislation mandating the 30% solution has not been signed into law despite several attempts.  Yet even the threat of a Federal mandate has been enough to motivate the ICC and ASHRAE to dramatically change their energy requirements. 

The main result of these latest changes is that wall framing in almost every building and climate zone will be required to have a significant amount of exterior continuous foam insulation.  The Steel Framing Alliance made the argument that there is a practical limit to how much foam insulation can be applied over a wall frame without introducing concerns over fire-resistance and structural attachment of siding.  Further, nearly every major siding manufacturer has limitations on the amount of foam they allow (typically 1 inch or less) as an underlayment.

Although we were able to obtain some concessions limiting the thickness of foam insulation, the industry was still faced with the predicament of not having approved methods for attaching siding through as much as 3 or 4 inches of foam.  The issues affect wood and steel framing, although they tend to impact steel to a greater degree.  In either case, without some changes to the requirements for siding attachment, there would be a significant disconnect between the energy and building sections of the codes.  Designers would be left to develop custom solutions without much guidance.  Inspectors would be faced with approving energy code provisions that could be in violation of the building section of the code.  

Responding to the need for solutions, SFA teamed up with the New York State Energy Research and Development Authority (NYSERDA) to co-fund a research effort for attaching siding through as much as 4 inches of foam.  Providing solutions for vinyl, metal, fiber-cement, wood, and stucco  siding materials was the primary focus of  the research.  Brick, EIFS or other materials not depending on fasteners to directly support their dead load were not addressed.  Newport Ventures of Schenectady, NY and Applied Residential Engineering Services (ARES) of West River, MD were assigned the research project.

After several months of assessing different options, the research team determined two different approaches that can be used to address the loads that would be seen with typical siding materials. 

  1. Fasteners directly applied through siding and the underlying foam into the framing.  This is not drastically different from current practice except before this research little was known about the adequacy of long fasteners effectively supporting a load a significant distance from the wall, with only foam insulation in between. 
  2. Use of hat channels or other furring attached through the foam and into the framing.  This solution would allow existing practices for siding attachment to continue to be used since the hat channel would provide the surface for siding attachment.

Both options require some added cost over existing practice.  Most of the cost is related to the fact that the foam insulation is now required and it increases the thickness of the walls.  Details at window, door and other openings need to be addressed in the design stage to account for thicker walls.  Some architectural detailing is necessary as well, such as making sure the desired roof overhang is maintained  with the addition of the foam on the outside of the wall, and detailing at the top and bottom of the foam.  Gable end walls may need to be designed different than in the past to account for a potentially abrupt termination of the foam at the top of the conditioned section of the wall.

Test and analysis program

The research team developed a list of pros and cons of the two options.  Subsequently, a group of contractors was invited to evaluate the solutions on a small scale mock-up of different wall configurations.  Once the team was certain that the solutions were feasible for contractors to install, they retained the services of a test laboratory, Progressive Engineering, Inc. of Goshen, Indiana (PEI) to conduct structural tests of the assemblies. 

PEI test results were very promising for both solutions.  As part of the testing, PEI also looked at the possibility of direct attachment of siding to OSB or similar sheathing materials.  The uncertainty of the results with direct attachment of OSB ruled out this solution until more testing can be conducted in the future.

According to Jay Crandell of ARES, the primary researcher on the project, “The results of this testing and evaluation have helped to fill a gap in the available knowledge related to fasteners when the siding is not directly in contact with the underlying sheathing or framing.  The CFS industry can now move forward with siding attachment solutions that allow the structure to meet or exceed new energy code requirements”. 

Mark Nowak, President of SFA, cited the importance of having this research available at the present time.  “The Foam Sheathing Coalition (FSC) submitted a code change proposal to the 2012 IRC and IBC code change committees proposing solutions for siding attachment in the latest code change cycle.  Unfortunately, CFS framing was not part of their proposal, putting us at a potentially serious disadvantage relative to our competition.”

Without this research, the next opportunity to include CFS would be in the 2015 ICC codes.  SFA subsequently worked with the FSC to modify their proposals to the 2012 codes to include steel framing.  The modified proposals were submitted to the ICC in February of this year and will be heard at the final action hearings in Dallas this May. A final action hearing agenda including the joint FSC/SFA public comment on ICC code proposal FS156-09/10 is available at www.iccsafe.org.

The research supporting the public comments to the ICC is available for viewing on the SFA website at the following link Building Energy-Efficient Structures through the Use of Continuous Insulation.

In addition to the direct introduction of solutions for CFS framing into the codes, SFA plans to work with the AISI Committee on Framing Standards to further assess the test data and expand the number of solutions available to designers.  In the future, additional testing and evaluation of attachment directly to OSB sheathing is likely to yield solutions that can be even more cost-effective.

This siding research is one of several research projects now underway by SFA and allied organizations to address major barriers and opportunities for CFS framing.  Much of this work began in mid to late 2009 and is just now becoming available. 

Look for updates on other research in Framework Online over the next few months as more of these projects are completed and ready for dissemination.

Editor, Framework Online

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Brought to you by the Steel Framing Alliance (SFA) on the first Wednesday of each month, February through December. Framework Online arms you with important news and commentary on the cold-formed steel (CFS) framing and construction industries.