On January 1, 2019, the 2018 North Carolina Building Code (based on the 2015 IECC with amendments) went into effect. This new code should stay for at least 3 years, since NC typically runs a 3-year code cycle, and the 2012 NC building code was in effect for 6 years.
Insulation Requirements for NC Building Code
The building code requires structures to have certain R-values* for the state based on different locations and climates. Wake County is a 4A zone, so walls, floors, ceilings, and slab insulation values are unchanged from the 2012 code.
Insulation R-Values for NC Building Code
- R-19 on floor system/garage ceiling
- R-15 on exterior walls
- R-38 for the ceiling/attic
So what does this mean for MPI Foam?
We run a performance calculation of the insulation envelope for our inspectors during the insulation inspection, since the spray foam that is installed typically doesn’t meet the prescriptive R-values in the walls and roof decks.
However, spray foam insulation normally performs much better than its prescriptive R-value because of the air sealing properties, as well as its ability to create a complete fill on the walls and in roof cavities.
To prove our spray foam insulation distributed within walls, floors, and roofs exceeds the current 2018 NC Building Code R-values, we have a third party energy rater run a performance or energy calculation.
*R-Value: The capacity of an insulating material to resist heat flow. The higher the R-value, the greater the insulating power.
This article was updated in December 2021.Go back