Updated ceiling insulation requirements for alterations in vented attics.

• R-49 ceiling insulation in climate zones 1-3, 6, 8-16. Exception of verified R-19 in climate zones 1, 3, and 6. Section 150.2(b)1Ji.
• Seal all accessible areas of ceiling plane between attic and conditioned space in climate zones 2, 4, and 8-16. Exception 1 and Exception 2. Section 150.2(b)1Jii.
• Insulate over recessed lighting to match ceiling insulation in climate zones 1-4 and 8-16. Use a fire-proof cover if the fixtures are not I-C rated. Section 150.2(b)1Jiii.
• Attic ventilation complies with California Building Code requirements, with exceptions.

1. An exception was added that exempts Junior Accessory Dwelling Units (JADUs) that are classified as additions to an existing building from whole-building mechanical ventilation requirements. JADUs are dwelling units that are no more than 500 square feet and contained entirely within an existing single-family building,
2. New language clarifying when whole-dwelling unit mechanical ventilation and local mechanical exhaust requirements must be met for additions and alterations.

1. The trigger for duct insulation and duct sealing requirements has been revised from 40 feet to 25 feet of altered ducts. The duct requirements apply when any length of duct is extended to serve an addition.
2. Duct insulation levels have been revised. Climate zones 3 and 5-7 require R-6. All other climate zones require R-8.
3. Duct leakage targets have been revised. The duct leakage must now be equal to or less than 10 percent of the system airflow, or the duct leakage to outside must be equal to or less than 7 percent of system airflow.
4. Electric resistance space heating is prohibited as the primary heat source. Replacement space heating systems must be gas or heat pump unless one of the exceptions are met.

1. Expand the cool roof requirements for steep-sloped roof replacements to Climate Zones 4 and 8-9. The allowable exceptions were also revised.
2. Expand the cool roof requirements for low-sloped roof replacements to Climate Zones 4, 6-12 and 14. The allowable exceptions were also revised.
3. Add a new requirement for roof deck insulation for low-sloped roof replacements in Climate Zones 1, 2, 4, and 8-16. R-14 continuous roof deck insulation or and equivalent assembly roof assembly U-factor of 0.039 is required. Various exceptions to this requirement are allowed.
4. Changes to when replacement electric resistance space heating equipment is allowed when the existing equipment is electric resistance.
5. Reduce the duct sealing target for altered duct and space conditioning systems from 15% to 10% of total duct leakage in all climate zones.
6. Increase the prescriptive duct insulation from R-6 to R-8 in Climate Zones 1-2, 4, 8-10, and 12-13.
7. Reduce the 40-foot trigger for prescriptive duct sealing and insulation to 25-feet for altered systems. Eliminate the minimum length requirement for additions and require duct sealing whenever an existing duct system is extended to serve an addition.
8. Add a prescriptive requirement for insulation and sealing in vented attics for altered ceilings or when an entirely new or complete replacement duct system is installed in a vented attic. The requirements apply in all climate zones except 5 and 7. Various exceptions to this requirement are allowed.
9. New doors that result in an increase in exterior door area must meet the newly constructed buildings requirement of a maximum U-factor of 0.20.

New, more specific language specifying which water heating systems are allowed prescriptively