Does every ADU need a Title 24 report?

Almost always, because an ADU either creates new conditioned space or alters regulated components. Your building department makes the final determination for your project.

What does Title 24 compliance mean for an ADU?

Showing on a CF1R at plan check that the unit meets the 2025 Energy Code for how it is built: a new detached ADU as a new building, an attached ADU or garage conversion as an addition, and a JADU inside the house as an alteration. Installers, an ECC-Rater where required and the building inspector then confirm it during construction.

Is a garage conversion treated differently?

Yes. Converting an unconditioned garage into an ADU is treated as an addition rather than new construction, so the solar requirement does not apply. Converting space that was already conditioned is an alteration.

Do I need solar on my ADU?

Newly constructed detached ADUs prescriptively require solar PV unless an exception applies. Attached additions and conversions are treated differently. We confirm which applies to your project.

How much does an ADU report cost?

From $199, including up to 1,000 sq ft. Above that, each additional 100 sq ft is +$9, shown in the order form before you pay.

ADU Title 24 Energy Reports

Compliance documentation for detached ADUs, attached ADUs, garage conversions and JADUs — prepared for the 2025 Energy Code and priced from $199.

Choose your report
Upload your plans
Pay securely
Permit-ready report by email

Accessory dwelling units are the single most common Title 24 project in California, and they are also the one most often documented incorrectly. The reason is that an ADU is not one thing under the Energy Code. Depending on how it is built, the same 700 sq ft unit can be treated as a newly constructed building, an addition, an alteration, or space created entirely within an existing conditioned envelope — and each of those carries different requirements.

Title 24 compliance for an ADU in California

Title 24 compliance for a California ADU means showing, before the permit is issued, that the unit meets the 2025 Energy Code for what it is in energy terms: a new building, an addition or an alteration. The Energy Code has no ADU category of its own, so the way the unit is built decides the rules. The design is documented on a CF1R certificate of compliance at plan check. During construction the installers complete CF2Rs, an ECC-Rater tests any measures the CF1R lists for verification, and the building inspector signs the work off at final; what happens after you receive your report walks through those stages.

The 2025 Energy Code applies to every ADU whose permit application is submitted on or after 1 January 2026. Size, setbacks and height are state ADU law rather than Title 24, covered in California ADU rules and Title 24.

How your ADU is classified

Detached new construction — a standalone unit built from scratch. It is a new single-family building and meets the new-construction requirements in full, including newly installed solar PV unless an exception applies.
Detached ADU Title 24 report →Does an ADU need solar? →
Attached addition — conditioned floor area added to the existing house, sharing a wall, floor or ceiling with it. It follows the addition rules and solar PV is not required.
Attached ADU Title 24 report →ADU above a garage →
Garage or basement conversion — unconditioned space brought into conditioned use, attached or detached. The code treats it as an addition, so solar PV is not required, and walls that keep their existing siding can use an exception to the continuous insulation requirement.
Garage conversion ADU Title 24 →
Junior ADU within the house — a JADU of up to 500 sq ft carved out of the existing home. That is an alteration, judged on what the work changes; any part taken from an attached garage is an addition.
JADU Title 24 requirements →

Getting the classification wrong is the most common cause of an ADU energy correction at plan check, because an alteration, an addition and new construction trigger different requirements. Do ADUs need Title 24? walks through each case.

Two rules apply whichever type you build. A system serving the ADU needs its own thermostat, and the Mechanical Code does not allow return air from one dwelling unit to be discharged into another, so an attached ADU generally cannot share the main house's ducted system. And a vented range hood in an ADU has its certification, airflow and sone (noise) rating verified by an ECC-Rater.

Solar on detached ADUs

Newly constructed detached ADUs must have newly installed solar PV to meet the prescriptive requirements, unless an exception applies. Whether an exception applies to your project depends on the specifics, and it is one of the first things we check. If solar is not viable on your site, the performance compliance path may still get you there — we will tell you which route your project needs.

What you receive

A permit-ready CF1R Certificate of Compliance for your scope, registered where your project requires it, delivered by email as a PDF. Revisions are unlimited until your project complies, because ADU plans almost always move between the first model and the final permit set.