CSLB C-39 Roofing ContractorFlashing, Ventilation and InsulationHard
Under Title 24 prescriptive requirements, a builder is installing ceiling insulation in a new wood-framed attic assembly for a single-family residence in most California climate zones. What is the typical minimum required insulation value for this application?
- AR-19
- BR-38
- CR-13
- DR-30
Show answer & explanationAnswer & explanation
Correct answer: B. R-38
Title 24 prescriptive requirements for new wood-framed ceiling/attic insulation in most California climate zones call for a minimum of R-38, reflecting the state's emphasis on reducing heating and cooling energy loads through the ceiling/attic assembly.
Why the other options are wrong
- A. R-19 is below the current prescriptive ceiling requirement for most zones.
- C. R-13 is typical for wall cavity insulation, not attic ceilings.
- D. R-30 is sometimes used in specific milder zones but not the general standard.
Title 24 Prescriptive Ceiling Insulation
The minimum insulation R-value required for new wood-framed attic/ceiling assemblies under California's Title 24 prescriptive path, commonly R-38 for most climate zones.
- R-38 is the typical prescriptive ceiling minimum statewide
- Wall insulation requirements are typically lower (e.g., R-13 to R-21)
- Climate zone and compliance path (prescriptive vs. performance) can adjust exact values
Memory trick: Attics need the thickest blanket — think R-38 up top.