QII (Quality Insulation Installation) is a set of inspections where an ECC rater, formerly called a HERS rater, checks your air sealing and insulation before the walls are closed. Under the 2025 California Energy Code, it is required for new homes and for additions over 700 square feet when the project follows the prescriptive rules.
Sources are Chapter 3 of the CEC's 2025 Single-Family Compliance Manual, Section 150.2 of the Energy Code, Reference Appendix RA3.5 and the CEC's ADU FAQ.
What does a QII inspection check?
Two things, both verified in the field by the rater:
- Air sealing. A continuous air barrier around the whole building envelope: walls, ceiling or roof, and floors.
- Insulation installation. Insulation that fills the cavity, touches the air barrier and meets the R-values on the plans.
The compliance manual names four common flaws QII is meant to catch:
- Gaps or holes in the air barrier.
- Insulation not touching the air barrier, leaving an air space.
- Voids and gaps in the insulation.
- Compressed insulation.
If slab edge insulation is installed, the rater checks that too.
When is QII required?
| Project | QII under the prescriptive rules |
|---|---|
| New home or new detached ADU | Required, all climate zones |
| Addition over 700 sq ft | Required for the addition |
| Addition of 700 sq ft or less (including attached ADUs and garage conversions) | Not required |
| Alteration, such as new insulation in an existing attic | Not required by this rule |
The manual says Table 150.1-A "calls for QII in all climate zones for newly constructed buildings and additions greater than 700 square feet." For smaller additions, Section 150.2(a)1Bv says the QII requirement does "not apply."
The credit catch. The CEC's ADU FAQ says that if your report models QII "for a compliance credit," a rater must still verify it, even on a small addition. Check the ECC section of your CF1R.
Can I skip QII on a new home?
Only through the performance approach. The manual says "QII is not a mandatory requirement," so it can be traded off. But the software assumes QII in the standard design and "automatically reduces the effectiveness of insulation" when you skip it. Something else, such as better windows or equipment, has to make up that loss.
What about garage conversions?
A garage conversion is an addition. If it is 700 square feet or less, prescriptive QII does not apply. Over 700 square feet, Section 150.2(a)1Av eases two parts of QII for spaces converted from unconditioned to conditioned:
- Existing window and door headers do not have to be insulated.
- Air sealing is not required where the existing air barrier is not being removed or replaced.
See garage conversion reports for the other rules.
When does the rater come out?
While the framing is open. The CEC has separate QII forms for each stage:
- CF2R-ENV-21-H and CF3R-ENV-21-H: air infiltration sealing, framing stage.
- CF2R-ENV-22-H and CF3R-ENV-22-H: insulation installation.
The installer signs the CF2R and the rater signs the matching CF3R. The manual says the "air barrier must be verified prior to insulation being installed," and RA3.5 says the procedures must be field verified before the permit is finaled. Once drywall is up, the rater cannot see what QII checks.
For how QII fits with other rater visits on an ADU, see ECC (HERS) rater testing for an ADU.
How do I pass QII the first time?
These tips come from RA3.5 and the compliance manual:
- Insulate hard spots early. Corners, wall intersections and the exterior wall behind a tub or shower usually have to be insulated before the tub, the exterior sheathing or the stucco lath goes on.
- Air barrier behind tubs and showers. RA3.5 requires one on the inside of exterior walls next to the tub or shower enclosure.
- Fit around obstructions. Cut or split batts around wiring, pipes and boxes. Compression is limited to 30 percent of the insulation's thickness.
- Fill narrow gaps. Spaces under 2 inches wide, such as at corners and where interior walls meet exterior walls, need snugly fitted insulation or low-expansion foam.
- Insulate behind electrical boxes that are shallower than the cavity.
- Plan headers. QII accepts several header designs, such as two-member headers with insulation between them. Single-member headers narrower than the wall need at least R-3 in 2x4 framing or R-5 in other assemblies.
- Show structural steel on the plans. Metal bracing and steel framing are allowed if they are on the structural plans and insulated to limit thermal bridging.
- Have product data ready. The installer must show the rater the air barrier materials and insulation R-values.
Who arranges QII?
The builder or owner-builder hires the rater, and the insulation installer follows the RA3.5 procedure. Book the rater when you schedule insulation, not after. If you are building it yourself, see Owner-builder Title 24.
Need a report that tells you whether QII applies? See our flat prices.
Frequently asked questions
What is QII?
Quality Insulation Installation. An ECC rater (formerly HERS rater) checks that the air barrier is continuous and that insulation is installed without gaps, voids or compression, following Reference Appendix RA3.5.
When is QII required?
Under the prescriptive rules, QII is required in all climate zones for newly constructed homes, including new detached ADUs, and for additions over 700 square feet. It does not apply prescriptively to additions of 700 square feet or less.
Does my garage conversion need QII?
Only if it is over 700 square feet, or if your report takes QII as a credit. Over 700 square feet, the code does not require existing window and door headers to be insulated, or air sealing where the existing air barrier stays in place.
Can I skip QII on a new home?
Through the performance approach, yes. QII is not mandatory, so it can be traded off. But the software assumes QII in the standard design and reduces insulation effectiveness when you skip it, so other features must make up the difference.
When does the rater inspect for QII?
Before the walls are closed. There are separate forms for air sealing at the framing stage and for insulation installation, and the CEC's manual says the air barrier must be verified before insulation is installed.
Related
Sources
- energy.ca.gov/filebrowser/download/8635?fid=8635
- energy.ca.gov/sites/default/files/2026-07/CEC-400-2025-010-F.pdf
- energy.ca.gov/sites/default/files/2025-07/CEC-400-2025-010-AP.pdf
- energy.ca.gov/programs-and-topics/programs/building-energy-efficiency-standards/energy-code-support-center-6/2025
- energy.ca.gov/programs-and-topics/programs/building-energy-efficiency-standards/2025-building-energy-efficiency-3