Page 8 - CodeWatcher Fall 2016 Issue
P. 8
Energy Code Minute
Ceiling Insulation:
“Prescriptive” Options
Here’s a quick primer on how to geOtpttiohne1: “rPigrehscrtipRtiv-ev” alue
in ceilings when following the Prescriptive Path of the
2009, 2012 and 2015 IECC. Ceilings with Attic Spaces
BY STEPHEN CARR
After conducting many code trainings Full height of insulation isInsulation
with local building officials, builders, not achievable.
and insulation companies throughout Credit: DOE’s Building Energy Codes University
the nation, I realized there was a Insulation
common question when it came to
ceiling insulation: “What R-value is No insulation over the
the right R-value when following the top plate.
Prescriptive Path?” So, I broke this
section of the code down and extended Figure 1
the answer to the other alternatives in
the code where the project may comply. Ceilings With Attic Spaces
There are two types of ceilings in
the Energy Code: ceilings with attic For ceilings with attic spaces in climate zones requiring
spaces and ceilings without attic a Prescriptive R-38 or higher, the insulation in the ceiling
spaces. Other than exceptions listed in assembly must follow the Prescriptive Method of the Code
the code, there are no trade-offs that Table R402.1.1 (2009 and 2012 IECC) or R402.1.2 (2015 IECC).
will lower these R-values more. The insulation either does not cover the top plate or it is
compressed to a level less than R-30.
8 CodeWatcher / Fall 2016
If your Energy Code calls for a Prescriptive R-38 in the
ceiling, then, as shown in Figure 1, that is the level to which
the main part of the attic will be insulated. The code is
assuming that near the eaves there will be less than R-38
and does not call out any requirements for that area. This
also applies for R-49 required jurisdictions as well.
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