New Detached ADU Title 24 Checklist
Work in this order: confirm the unit is new construction, test whether solar is required for your climate zone and floor area, fix the electrical service and water heater, put the ventilation and glazing inputs on the plan set, then line up the ECC-Rater. Each step feeds the CF1R, so a late change in one reopens the others.
- Choose your report
- Upload your plans
- Pay securely
- Permit-ready report by email
1. Confirm the class
The unit must be a new building with no shared wall, floor or ceiling with a dwelling. A breezeway does not change that. Note the climate zone from the street address, because every number below depends on it.
2. Test the solar threshold before drawing the roof
Section 150.1(c)14 sizes PV as floor area times a zone factor A, divided by 1,000, plus a zone factor B for the dwelling unit. No PV is required if the result is under 1.8 kWdc. Solving for floor area, the unit crosses 1.8 kWdc at about 212 square feet in zone 15, 718 in zone 9 and 1,265 in zone 5. Those figures assume an unshaded roof; shading, roof direction and the 80 square foot steep-roof limit can still remove the requirement. A battery of at least 7.5 kWh that meets JA12 lets the calculated size drop by 25 percent. Details are on ADU solar.
3. Fix the electrical service and equipment
- Service over 125 amps brings battery-ready wiring; a 200 amp panel needs a marked 225 amp busbar.
- Heat pump space heating, and a heat pump water heater with its tank in the garage or conditioned space. Gas appliances need electric-ready circuits.
4. Put the model inputs on the plan set
- Bedroom count, because ventilation airflow is 0.03 cfm per square foot plus 7.5 cfm for each bedroom plus one extra.
- Window schedule totalling no more than 20 percent of floor area.
- The range hood model, because its rating is verified.
5. Register and test
If any listed measure needs an ECC-Rater (the role formerly called a HERS rater), the CF1R is registered with an ECC-Provider before submittal. Book the rater early; the process after delivery is on what happens after your report.
The rules behind each step are on the detached ADU report page. Compare the addition versus new construction page, the ADU CF1R and ADU Title 24 reports.
Common Title 24 Questions
- Do ADUs need Title 24 in California?
- What plans are needed for an ADU Title 24 report?
- How much does an ADU Title 24 report cost?
- How long does an ADU Title 24 report take?
- Does a garage conversion ADU need Title 24?
- Does a JADU need a Title 24 report?
Frequently Asked Questions
No. PV is not required when the calculated size is under 1.8 kWdc, and other exceptions apply. In zone 5 a unit below about 1,265 square feet falls under it, assuming an unshaded roof.
The solar test, because it depends only on climate zone and floor area and can change the roof design, panel size and electrical plan.
Existing panels cannot. New modules added to that system on the same lot can, if they are part of the ADU permit and the utility allows it.
Explore ADU and JADU
- Do Pre-Approved ADU Plans Come With Title 24?
- Does a Prefab ADU Need Title 24?
- Prefab and Factory-Built ADU Title 24 Requirements
- Two-Story ADU Title 24 Requirements
- Title 24 for ADU Builders
View all ADU and JADU guides → · Permits and Compliance · Title 24 guide