Title 24 Guide for California Homeowners (2025 Code)

If you are building a new home, an ADU or an addition in California, or changing windows, heating or a water heater, your permit will probably need a Title 24 energy report. This guide explains what that report is, how it gets made, what happens after the permit, and how to keep it from slowing you down.

Each section is short. Where we have a deeper guide on a topic, we link to it instead of repeating it.

What is Title 24?

Title 24 of the California Code of Regulations holds the state's building standards. It has many parts. The one your energy report deals with is Part 6, the California Energy Code, written by the California Energy Commission (CEC). Other parts cover things like the residential building code (Part 2.5) and CALGreen (Part 11).

So when a plan checker asks for "Title 24," they almost always mean proof that your design meets Part 6. That proof is a form called the CF1R, the Certificate of Compliance. Our guide What is a Title 24 report? walks through what is inside one.

Which code applies to my project?

The date your permit application goes in decides it.

Permit application submitted	Code that applies
January 1, 2023 to December 31, 2025	2022 Energy Code
On or after January 1, 2026	2025 Energy Code

Everything below describes the 2025 Energy Code.

Who needs a Title 24 report?

The Energy Code applies to new buildings, additions and alterations. It does not apply to repairs.

Project	How the code sees it	Report usually needed?
New home or new detached ADU	Newly constructed building	Yes, usually a full computer model
Room addition, attached ADU, garage conversion	Addition (adds conditioned floor area and volume)	Yes
New windows, HVAC system, water heater, reroof, insulation	Alteration	Often, for the parts being changed
ADU or JADU built inside existing heated space	Alteration	Depends on what changes
Fixing broken glass in an existing frame	Repair	No

The rules for each kind of project are in When is Title 24 required?. Your building department makes the final call on what it wants to see.

The three ways to comply: mandatory, prescriptive and performance

Every project must meet the mandatory measures. On top of that, you pick one of two paths to show the rest of the design complies.

Mandatory measures apply no matter which path you choose. Examples from the CEC's 2025 single-family mandatory summary:

Minimum wall insulation: R-15 in 2x4 walls and R-21 in 2x6 walls (16 inches on center).
A maximum weighted average window U-factor of 0.40.
Sealed and tested ducts, and ducts kept out of the attic in homes with attics.
Whole-house ventilation and kitchen and bathroom exhaust.
High-efficacy lighting.
Electric-ready wiring where gas appliances are installed.

Prescriptive path. You meet a fixed list of requirements for your climate zone, item by item. It is simple and needs no modeling. The catch: there is no room to trade. If one window or one wall misses the list, the design fails. The CEC's manual says additions and alterations generally use this path.

Performance path. An energy consultant models the building in CEC-approved software. The software compares your design with a "standard design" of the same building in the same climate zone. If yours does as well or better, it passes. You can trade, for example better windows against a wall that cannot take more insulation. New homes using this path must use approved software, such as the CEC's free CBECC program or an approved third-party program like EnergyPro.

	Prescriptive	Performance
How it works	Meet every listed value	Model the whole building
Trade-offs allowed	No	Yes
Best for	Simple additions and alterations	New homes, ADUs, larger or harder additions
Output	A prescriptive CF1R (for example CF1R-ADD or CF1R-ALT)	CF1R-PRF-01 from the software

Under the 2025 code, the performance path scores the building on long-term system cost (LSC) and source energy. The design has to pass each target separately.

The forms: CF1R, CF2R and CF3R

Three forms follow your project from plans to final inspection.

Form	Official name	When	Who signs
CF1R	Certificate of Compliance	Before plan check	Responsible designer, plus the documentation author
CF2R	Certificate of Installation	During construction	Each installing contractor
CF3R	Certificate of Verification	Before final	An independent ECC-Rater

The CF1R must be part of your plans, and it must match them. The CF2Rs say each installer built what the plans show. The CF3Rs say a rater tested what needed testing. Our guide CF1R, CF2R and CF3R explained covers who signs each one and what happens if a test fails.

CHEERS and registration

When any feature on your project needs field testing, the forms must be registered with a CEC-approved ECC-Provider. The CEC approved CHEERS on November 12, 2025 as the ECC-Provider for the 2025 code. CHEERS runs the registry where the CF1R, CF2Rs and CF3Rs are stored.

What registration means for you:

The building department accepts only the registered CF1R. It shows a registration number.
Installers sign their CF2Rs in the same registry.
The rater enters test results there, and the registry produces the CF3R.
If nothing on the project needs testing, there is no CF3R and no registration.

The CEC allows one exception for urgent alterations such as an HVAC changeout: the certificates can be registered later, but before the permit is closed.

ECC (formerly HERS) field testing

An ECC-Rater is an independent tester who checks that certain features work as designed. The CEC's ECC Program replaced the HERS Program with the 2025 code, so you will still see "HERS rater" on many websites. It is the same kind of work.

Common items a rater tests on a home:

Duct leakage, when the home has ducts.
Refrigerant charge on heat pumps (all climate zones) and air conditioners (climate zones 2 and 8 through 15).
Airflow and fan power on ducted systems.
Quality Insulation Installation (QII), which has to be inspected before the walls are closed.
Kitchen range hood and whole-house ventilation airflow.

Your CF1R lists exactly which tests your project needs. For a ductless mini-split ADU, see ECC (HERS) rater testing for an ADU, which also explains how to need fewer visits.

Climate zones

California has 16 building climate zones. Your zone sets many prescriptive values, such as window U-factor, attic insulation and whether a whole-house fan is required. The same house can pass in one zone and fail in another.

Your zone comes from your address, not your city name. Some cities sit in more than one zone. Use the CEC's climate zone tool, or see our guide to California climate zones.

What changed in the 2025 Energy Code

These are the biggest changes for homes, taken from the CEC's "What's New for 2025, Single-Family" summary.

Area	What the 2025 code does
Heating	Prescriptive heating must be a heat pump in all climate zones, or the design must pass by performance
Windows	Prescriptive maximum U-factor is 0.27 in zones 1-5, 11-14 and 16, and 0.30 in zones 6-10 and 15
Windows (mandatory)	Maximum weighted average U-factor of 0.40, including skylights. Fire Hazard Severity Zones are excepted
Walls (mandatory)	2x4 walls need R-15 (U-0.095), 2x6 walls need R-21 (U-0.069)
Attics	Vented attic Option C: R-38 in zones 1 and 8-16, R-30 in zones 2-7. Cathedral ceilings R-38
Batteries	New single-family homes with one or two units and service over 125 amps must be battery-ready, unless a battery is installed
Solar PV	Required PV size is now based on the solar access roof area
Heat pumps	Defrost timers set to 90 minutes or more, and backup electric heat locked out above 35°F, with exceptions. The installer certifies both on the CF2R
Heat pump water heaters	New rules for backup heat with unconditioned inlet air, and for room volume or ventilation. Future HPWH circuits must be at least 30 amps
Additions	Gas tankless water heaters are no longer a prescriptive option for additions
Lighting	All luminaires must meet Joint Appendix JA8
Testing program	HERS is now the ECC Program, and raters are ECC-Raters

From design to final: the timeline

Design. Your designer draws the floor plan, elevations, window schedule and wall and roof sections. Bring in the energy consultant now if you want to test choices before they are locked in.
Energy report. The consultant builds the CF1R from the plans and picks the prescriptive or performance path.
Registration. If anything needs ECC testing, the CF1R is registered in CHEERS and signed online.
Plan check. The CF1R goes into the plan set, usually printed on full-size sheets. The plan checker compares it against the drawings.
Corrections. If the plan checker finds a mismatch, the plans or the report are revised and resubmitted.
Construction. Installers sign CF2Rs as they finish their work. Some ECC tests, like QII, happen before drywall.
ECC testing. The rater tests the flagged items and registers the CF3Rs.
Final inspection. The inspector checks that the required forms are complete. The building department cannot issue the certificate of occupancy until all required CF3Rs are in.

How long plan check takes depends on your city. Our city pages list how each one accepts submittals.

What does it cost?

Plan for three separate costs:

The energy report. Prices depend on project type, size and whether it needs a full model.
ECC rater testing. Billed by the rater, often per visit or per test.
CHEERS fees. Usually built into the rater's price.

Equipment the report calls for, like a heat pump water heater or a battery-ready panel, is a construction cost. Our guide How much does a Title 24 report cost? breaks down published market prices and CHEERS fees.

Common plan-check corrections, and how to avoid them

Most energy corrections are not about the design. They are about paperwork that does not match. Los Angeles County's 2025 energy correction sheet for single-family buildings is a good map of what plan checkers look for.

The CF1R does not match the plans. The window schedule must show the same U-factor and SHGC as the CF1R. HVAC and water heater efficiencies must appear on the plans too.
The CF1R is not on the plan sheets. Many departments want it printed on the drawings, not taped or stapled in.
Missing signatures. The responsible designer and the documentation author must both sign.
Unregistered CF1R. If the project needs ECC testing, only a registered copy is accepted.
Wrong climate zone. Check the address in the CEC tool, not the city name.
Mandatory measures missing. Some departments want the mandatory measures written as notes on the plans.
Old software version. The report must be run in a version the CEC currently approves.

Our full list, with fixes, is in Title 24 plan-check corrections.

How to make the process smoother

Send complete plans: floor plan with dimensions, elevations, window sizes and wall and roof sections. Our Title 24 document checklist lists what to send for each project type.
Decide your heating, cooling and water heating equipment early. The report depends on it.
Tell your consultant about any change to windows, insulation or equipment. A changed plan means a revised CF1R.
Book your ECC-Rater before construction starts, so tests that must happen before drywall are not missed.
Keep the registered forms together for the final inspection.

Title 24 for your project type

ADUs: detached, attached, garage conversion and JADU rules, including solar.
Garage conversions: treated as additions.
Home additions: size-based rules from 400 to over 700 square feet.
New homes: solar PV, battery-ready and performance modeling.
Window replacements: the U-factor and SHGC rules for new and replacement windows.

Glossary

Term	Plain meaning
Addition	Any change that adds conditioned floor area and volume
Alteration	A change to the envelope, heating, cooling, water heating or lighting that is not an addition
BESS-ready	Wiring and panel space for a future home battery
CF1R	Certificate of Compliance, the Title 24 report
CF2R	Certificate of Installation, signed by installers
CF3R	Certificate of Verification, signed by the ECC-Rater
CHEERS	The CEC-approved ECC-Provider that runs the registry
Climate zone	One of California's 16 energy zones, set by address
Conditioned space	Space that is heated or cooled
ECC	Energy Code Compliance, the program that replaced HERS
ECC-Rater	Independent field tester, formerly called a HERS rater
LMCC	The compliance certificate for low-rise multifamily buildings
LSC	Long-term system cost, one of the 2025 performance scores
Mandatory measures	Rules every project must meet, whichever path it uses
NFRC label	The sticker that lists a window's rated U-factor and SHGC
Performance path	Compliance by computer model, with trade-offs allowed
Prescriptive path	Compliance by meeting a fixed list, item by item
QII	Quality Insulation Installation, inspected by a rater before walls close
SHGC	Solar heat gain coefficient: how much sun heat a window lets in. Lower blocks more
U-factor	How fast heat moves through a window or wall. Lower insulates better

Ready to start your report? See our flat prices.

Frequently asked questions

What does Title 24 mean on a home permit?

Title 24 is California's building standards code. On a home permit it almost always means Part 6, the Energy Code. Your building department wants a Title 24 report (the CF1R) to show the design meets it.

Which version of the Energy Code applies to my project?

It depends on when your permit application went in. The CEC says applications submitted on or after January 1, 2026 must comply with the 2025 Energy Code. Applications submitted from January 1, 2023 through the end of 2025 follow the 2022 code.

Do I need a Title 24 report for a repair?

No. The CEC's 2025 compliance manual says the Energy Code does not apply to repairs. Replacing broken glass in an existing window frame is a repair, as long as the new glass performs at least as well as the old.

Is an ECC-Rater the same as a HERS rater?

Yes. The CEC's Energy Code Compliance (ECC) Program replaces the HERS Program, starting with the 2025 Energy Code. The field testing is the same kind of work under a new name.

Does a duplex need a CF1R or an LMCC?

Usually a CF1R. The 2025 Energy Code defines a single-family building to include an Occupancy Group R-3 building with two or fewer dwelling units, plus townhouses. Multifamily forms are for buildings the code defines as multifamily, such as Occupancy Group R-2.

Can I start the Title 24 report before my plans are final?

Yes, and starting early can catch problems while they are cheap to fix. The report must match the plans you submit, so any change to windows, insulation or equipment after that means a revised report.

The complete Title 24 guide for California homeowners