Does the code require continuous insulation and prohibit the use of concrete masonry units (CMU) with integral insulation?
No.
The International Energy Conservation Code (IECC) provides several different, independent
methods of complying with the minimum energy efficiency requirements for commercial
construction: Prescriptive, Trade-Off, and Whole Building Energy Analysis. These alternatives are
permitted for each of the various editions of the IECC. The prescriptive method is often the
easiest to apply, but offers the least flexibility and most conservatism of the three options. If a
building envelope does not comply using either the prescriptive R-Value or U-Factor requirements,
another option is to use a software tool such as COMcheck.
Determine which version of the IECC applies to the location of your project.
IECC 2009 - Section 502.2.3 states the following: "The R-value of integral insulation installed in
concrete masonry units (CMU) shall not be used in determining compliance with Table 502.2."
IECC 2012 - Section C402.2.3 states the following: "The R-value of integral insulation installed in
concrete masonry units (CMU) shall not be used in determining compliance with Table C402.2."
The code does not prohibit the use of CMU with integral insulation. It only prohibits the use of CMU
with integral insulation in determining compliance with Table 502.2 or C402.2. Those Tables are used to
determine the R-value requirements of the insulation for wall assemblies, which for a mass wall would
be continuous insulation in a cavity wall or insulation installed on the exterior of the CMU wall.
Options that are allowed by Code to show compliance include the following:
2009 Edition of IECC
To utilize CMU with integral insulation, without continuous insulation, using the prescriptive path of
compliance, Table 502.1.2 must be used per Section C502.1.2 U-factor alternative.
2012 Edition of IECC
To utilize CMU with integral insulation, without continuous insulation, using the prescriptive path of
compliance, Table C402.1.2 must be used per Section C402.1.2 U-factor alternative.
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