Residential Building Inspector B1Building Planning and Life SafetyMedium
A residential building inspector is reviewing plans for a new single-family dwelling. The plans indicate that the dwelling will have a conditioned floor area of 2,500 square feet and will be constructed with wood framing. What is the minimum required R-value for the ceiling insulation in Climate Zone 5?
- AR-38
- BR-60
- CR-30
- DR-49
Show answer & explanationAnswer & explanation
Correct answer: D. R-49
According to the 2021 IRC, Table N1102.1.3 (R402.1.3) Insulation and Fenestration Requirements by Component, Climate Zone 5 requires a minimum ceiling insulation R-value of R-49 for new construction.
Why the other options are wrong
- A. R-38 is required for some walls or ceilings in lower climate zones or for certain cavity types.
- B. R-60 exceeds the minimum requirement and is typically for colder climate zones or specific high-performance constructions.
- C. R-30 is typically insufficient for ceiling insulation in Climate Zone 5.
Ceiling Insulation R-value
The measure of thermal resistance for ceiling insulation, indicating its ability to resist heat flow, which is crucial for energy efficiency.
- R-value requirements vary by climate zone.
- Higher R-value indicates better insulation performance.
- Specified in IRC Table N1102.1.3 (R402.1.3).
Memory trick: Climate Zones dictate R-values, keeping homes cozy or cool.