Who hires the ECC-Rater on an ADU, the builder or the owner?

On a new ADU or an addition, Reference Appendix RA2.5.1 puts the booking on the builder, before the measures are installed. Owners or their agents may carry out the builder steps only on alterations.

Does a small detached ADU need an ECC-Rater visit?

Plan for one. Whole-dwelling ventilation airflow is verified on every newly constructed dwelling unit and the Energy Commission states no size exception, and a heat pump needs refrigerant charge verification in every climate zone.

Can I sample identical ADUs on different lots?

Do not count on it. The manual limits sampling to newly constructed units of similar design in the same subdivision built by the same subcontractor, and the appendix keeps a group within one jurisdiction and one subdivision or multifamily development.

Title 24 for ADU Builders

Q: Can I sign my subcontractors' CF2Rs?

The manual lets the builder sign for the specialty subcontractors it hires, but the preparation and signature responsibility stay with the subcontractor who did the work. Anyone else signing for you needs a written authorised-representative agreement held by the ECC-Provider.

An ADU business meets the same Energy Code paperwork on every job, and the code puts the installation certificates, and the booking of the rater, on the builder.

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Permit-ready report by email

We prepare and register the CF1R. Three things then decide whether it holds: you sign the CF2R installation certificates, an ECC-Rater tests what the CF1R lists and signs the CF3R, and the inspector checks the building against all of it. This page is for the person doing the building.

What you sign

The CF2R is yours

Section 10-103(a)3 puts the installation certificate on the person in charge of the installation. The manual lets a builder sign for the specialty subcontractors it hires, but the preparation and signature responsibility stay with the subcontractor who did the work. Anyone else signing for you, the ECC-Rater included, needs a written authorised-representative agreement held by the ECC-Provider (Section 10-103(a)3A).

At handover

At final the builder leaves the certificates, a schedule of the interior luminaires and lamps, and ventilation instructions in the building (Section 10-103(b)).

Booking the ECC-Rater

You book, before the work goes in

RA2.5.1 tells the builder to arrange the rater before the measures are installed, and RA2.6.1 to hand over the registered CF1R and the subcontractors’ license numbers. Owners take over those steps only on alterations (RA2.8). The Commission expects the rater to contract with the builder, not subcontractors.

A new ADU always has something to test

Whole-dwelling ventilation airflow is verified on every new dwelling unit whatever its size (Section 150.0(o)2A), and a heat pump needs refrigerant charge verification in every zone. One ADU cannot be sampled.

Classification traps

Deep conversions and existing walls

The manual warns that an alteration stripped of all wallboard, insulation and exterior walls can be treated as a new building, and existing walls around newly conditioned space count as new, so the Section 150.0(c) minimum of R-15 in 2x4 framing applies.

The 2025 changes that reach the job

What you test and install

You certify on the CF2R that heat pump defrost and lockout controls were tested (Section 150.0(h)6 and 7). Section 110.3(c)7 sets backup heat and ventilation for water heaters in closets. Battery-ready wiring applies only above 125 amps of service.

State clocks and the Energy Code

Permit timing does not excuse Part 6

HCD’s handbook gives 15 business days for completeness and 60 days to approve or deny. A denial must list every defect, and a new application resets the count. Nothing in it waives Part 6.

How to order

What to send

Order the ADU report from $199, with unlimited revisions and a 24-hour rush at +$95. Send the plans as PDFs with the address, the window schedule, equipment models and roof layout. Send field changes before installation.

Classification first: detached ADUs, attached ADUs and garage conversions. For testing, read how to prepare for the ECC-Rater and what a CF2R is. Homeowners start at building your first ADU, and Title 24 for contractors covers repeat orders.