What you're looking at
A section cut through a 2x6 wood-framed exterior wall, drawn from interior (left) to exterior (right). The five labeled layers are the ones the Title 24 2025 compliance engine evaluates when this assembly is referenced in the model.
Why this is the prescriptive baseline
The Title 24 standard design names this wall (or its R-15+R4 CI / 2x4 sibling) as the exterior-wall construction in every California climate zone except CZ3, CZ5, CZ6, and CZ7. In the rest of the state, the 2x6 cavity plus R-5 continuous insulation is what the rule-comparison expects.
What changes if you skip the CI
Stripping the R-5 continuous insulation drops the assembly from R-26 to R-21 total. That can still pass under the Hybrid design option (which strips CI everywhere and carries compliance with HVAC + DHW upgrades instead), but it fails the prescriptive package.