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Vol. I ·California ADU Desk ·Licensed · Bonded · Insured ·CSLB #1098432 ·BBB A+ Accredited ·120+ ADUs Delivered ·Starting $250K ·10–16% ROI ·Los Angeles ·Bay Area ·Vol. I ·California ADU Desk ·Licensed · Bonded · Insured ·CSLB #1098432 ·BBB A+ Accredited ·120+ ADUs Delivered ·Starting $250K ·10–16% ROI ·Los Angeles ·Bay Area ·
GoldenStateADU

Design · 10 min read · March 3, 2026 · 444 words

Title 24 for ADUs: what actually triggers compliance

California's energy code is the single biggest design constraint after setbacks. Here's what Title 24 Part 6 requires for new ADUs in 2025 — heat pumps, fenestration, envelope, and the CF1R signoff.

Key takeaways

  • Walls: R-21 cavity + R-5 continuous insulation in CZ8/9 (covers most of LA).
  • Roof/ceiling: R-38 cavity for vented attics, R-30 + cool roof for unvented.
  • Slab edge: R-7 to a depth of 16 inches.

California's Title 24 Part 6 Energy Code is enforced on every new ADU. The 2022 code (in effect since Jan 1, 2023) made heat pumps the prescriptive default. The 2025 update, effective Jan 1, 2026, tightens envelope requirements and pushes solar-ready provisions further. This guide covers what triggers compliance and what an LADBS plan checker actually looks for.

Prescriptive vs performance path

There are two routes to compliance. The prescriptive path is a checklist of minimum components (R-values, U-factors, equipment efficiencies). The performance path runs an energy model in CBECC-Res and shows the design beats a code-defined baseline. Most detached ADUs use the prescriptive path; attached ADUs and conversions usually need performance modeling.

Heat pumps are the new default

Under the 2022 code, gas furnaces and gas water heaters are still legal but trigger compliance penalties on the energy budget. The path of least resistance is a heat pump space heater (mini-split or central) and a heat pump water heater. The ENERGY STAR cold-climate heat pump list is a good starting point — though LA basically never needs cold-climate models.

Envelope requirements at a glance

  • Walls: R-21 cavity + R-5 continuous insulation in CZ8/9 (covers most of LA).
  • Roof/ceiling: R-38 cavity for vented attics, R-30 + cool roof for unvented.
  • Slab edge: R-7 to a depth of 16 inches.
  • Windows: U-factor ≤ 0.30, SHGC ≤ 0.23 (west and south orientations).
  • Air leakage: blower-door tested at ≤ 5 ACH50.

Solar-ready and EV-ready

ADUs detached from the primary dwelling are required to comply with solar-ready provisions: a clear roof area facing within 110° of true south. ADUs are exempt from the actual PV requirement that applies to new single-family homes — but if the primary dwelling triggers it, an LADBS plan checker may ask. EV charging: a single 240V outlet in an accessible location is the minimum for any new ADU with a parking space.

The CF1R signoff

Every Title 24 submittal needs a Certificate of Compliance (CF1R) signed by a Certified Energy Analyst. This is the document LADBS stamps. Plan check rejects almost always trace back to a CF1R that doesn't match the architectural drawings — windows on the floor plan that aren't on the CF1R, or HVAC equipment that isn't listed on the CEC Appliance Database.

Sources

  1. Title 24 Building Energy Efficiency Standards · California Energy Commission
  2. CBECC-Res Compliance Software · California Energy Commission
  3. ENERGY STAR Heat Pump Criteria · U.S. EPA
  4. California Association of Building Energy Consultants · CABEC
  5. CEC Modernized Appliance Database · California Energy Commission

FAQ · Design

Common questions on design

The questions readers send us most after this guide.

  1. I'm in an HPOZ — can I still build?
    Yes, but with design review. Historic Preservation Overlay Zones require Certificate of Appropriateness from the cultural heritage commission before permits issue. We've shepherded projects through Miracle Mile, West Adams, Whitley Heights, and Spaulding Square HPOZs. Add 8–12 weeks for the COA process.
  2. What setbacks and height limits apply?
    Statewide ADU law (AB 68/881) overrides most local restrictions: 4-foot side and rear setbacks, 16-foot height for detached one-story, 18-foot for two-story within ½ mile of transit. Front setbacks follow the underlying zone. We model your envelope at the schematic stage.
  3. Are you licensed and insured?
    Yes — CSLB #1098432, fully bonded, $2M general liability, and workers' comp on every site. BBB A+ accredited, member of NAHB and the LA chapter of AIA.
  4. Do you use one crew or subcontractors?
    We carry our own foreman, framers, and finish carpenters in-house. Specialized trades — MEP, roofing, glazing, solar — are long-standing subcontract relationships, the same crews on every project. You will know every face on your site by week three.
  5. How does the contract work?
    Two phases. Phase 1 is a fixed-fee design + permitting agreement (typically $18K–$32K depending on scope) that takes you from feasibility through permit-in-hand. Phase 2 is a fixed-price construction contract issued only after permits are approved — no surprise change orders for items we should have caught at design.

Sources & further reading

  • California Government Code §65852.2 — statewide ADU framework (ministerial review, 60-day clock).
  • LADBS — Accessory Dwelling Unit information bulletins and current permit fee schedule.
  • HCD — California Department of Housing & Community Development, ADU handbook (2024 update).
  • Internal data: 120++ ADU projects delivered across Los Angeles County, 2018–2025.

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