Title 24 for Legalizing Unpermitted Construction
Legalizing unpermitted construction means applying for a permit now, and the building department decides how the Energy Code treats the space: as a newly constructed building, an addition or an alteration. That label, not the age of the work, decides whether solar PV and several other requirements apply.
- Choose your report
- Upload your plans
- Pay securely
- Permit-ready report by email
The department picks the label
The Energy Commission's ADU guidance says unpermitted work must meet the Energy Code when a permit application is made now, and that the building department determines how compliance is demonstrated and whether an ADU must comply as a newly constructed building or as an addition. The Commission's definitions steer that call. A new detached structure is a newly constructed building, an attached unit or a converted unconditioned space is an addition, and a conversion of space that was already conditioned is an alteration.
What each label switches on or off
- Solar PV. A newly constructed detached ADU needs new PV under Section 150.1(c)14 unless an exception applies. Additions are exempt (Exception 6 to Section 150.2(a)).
- Roofing. An addition of 300 square feet or less skips the roofing requirements of Section 150.1(c)11.
- Existing heating and cooling. When an addition is served by extending an existing system, the existing equipment need not comply, but any duct extended from it must be sealed and tested.
- Mixed scopes. A garage unit legalized together with a house addition is modeled as separate zones in the compliance software.
Ask in writing before the drawings are finished
Put the question to the department: which label does it apply, and which CF1R scope will it accept? The certificate of compliance must be approved before the permit issues (Section 10-103(a)2A), and the department cannot sign off the final inspection of a house until compliance is verified (Section 10-103(d)2). That holds even though the work is already standing, so plan for any ECC field verification on the finished installation.
Where the rest is covered
The code edition that applies, evidence for what is inside the walls and the drawings to prepare are on the unpermitted work and as-built permits page. For a converted garage see garage conversion ADUs. Old insulation is the usual unknown, covered in an older home with unknown insulation. Our ADU Title 24 reports start from the drawings of what exists.
Common Title 24 Questions
- What is Title 24?
- Do I need a Title 24 report?
- How much does a Title 24 report cost?
- How long does a Title 24 report take?
- What is included in a Title 24 report?
- What plans do I need to upload?
Frequently Asked Questions
It depends on the label. A newly constructed detached ADU needs PV unless an exception applies, while an addition does not. The building department decides which label fits.
Not for the Energy Code label. The permit application date sets the edition, and the classification follows what the space is. State ADU law adds separate protections for units built before 2020.
Explore Existing Buildings
- Unpermitted HVAC or Water Heater Replacement: Getting It Permitted Now
- Adding Solar to an Existing Home: Title 24 Rules
- Title 24 for Legalizing an Old Garage Conversion
- Title 24 for Unpermitted Work and As-Built Permits
- Buying a Home With an Unpermitted Addition or Garage Conversion: Where Title 24 Fits
View all Existing Buildings guides → · Permits and Compliance · Title 24 guide