The 2027 Title 24 supplement is thin by law — except in CALGreen

California's next code change already has a shape — and it's an unusually predictable one. The 2025 edition of Title 24 took effect January 1, 2026. What follows isn't a new triennial edition; it's a set of supplements produced by the 2025 Intervening Code Adoption Cycle, and they carry a fixed effective date: July 1, 2027.

Here's the thing: this round is thin, and it's thin by law. If you've been bracing for a big 2027 change, you can mostly stand down. There's exactly one item worth flagging — and it's buried in CALGreen. (If you need the difference between an errata and a supplement, we walked through that separately.)

The calendar: nothing has passed yet

The Building Standards Commission has not adopted anything. As of now, the adoption vote is scheduled for the Commission's August 25–27, 2026 meeting. Two earlier meetings that had been on the calendar — July 15–16 and August 12–13, 2026 — were canceled.

So everything below is proposed, not final. The commission can approve a proposal, disapprove it, send it back for further study, or approve it as amended. Whatever survives that vote gets published as a supplement to the 2025 Title 24 and takes effect July 1, 2027. The 2025 edition itself runs through December 31, 2028.

Why it's thin: AB 130 drew the box

The reason this cycle is so quiet is a statute. AB 130 (Chapter 22, Statutes of 2025) amended Health and Safety Code §18942 to restrict what agencies may even propose in an intervening cycle. The statute now limits proposals to a defined set of categories:

• Changes for editorial or clarity reasons.
• Technical updates to existing code requirements.
• Emergency building standards.
• State Fire Marshal amendments to specified wildfire building standards, including the Wildland-Urban Interface Code (Part 7).
• Changes to incorporate errata or emergency updates to the national model codes (and related state amendments).
• Certain changes to administrative practices.
• Building standards needed to incorporate minimum federal accessibility requirements.

That's seven narrow categories — and new substantive policy isn't among them. (Separately, AB 130 added subdivision (g) to HSC §18930 — a moratorium on most residential building standards until 2031 — but that's a different lever.)

Run the 21 proposals in this cycle through that filter and you get exactly what you'd expect: cleanup. Administrative Code housekeeping, a Commission language fix in the Existing Building Code, and accessibility alignment threaded across the Building, Electrical, Mechanical, and Plumbing codes (Parts 2, 3, 4, and 5). Little that changes what a building has to do.

The one item that moves: CALGreen §5.409

Now the exception. CALGreen's embodied-carbon rules are scattered today. The whole-building life-cycle assessment path and the product-GWP prescriptive path live in Section 5.409, titled "Life Cycle Assessment." The existing-building reuse option sits separately in Section 5.105. The Commission's own proposal — docket BSC 03/25 — pulls them together.

The plan: consolidate all three embodied-carbon compliance paths into Section 5.409 and rename it "Embodied Carbon Reduction." The three paths get relabeled as options — Reuse of Existing Building, Product GWP (prescriptive), and Whole Building Life Cycle Assessment (performance). The reuse provisions move out of §5.105; the whole-building LCA path that lives at §5.409.2 today is proposed to be renumbered — the proposal's own worksheet points to it as "Section 5.409.4 (formerly Section 5.409.2)."

Verified against the BSC 03/25 Initial Statement of Reasons (CALGreen, Part 11), ITEM 9 — "BSC is proposing to consolidate all embodied carbon reduction provisions in Section 5.409 and rename it to Embodied Carbon Reduction." The current §5.409 title, "Life Cycle Assessment," is confirmed in the 2025 CALGreen text now in effect.

None of this is new obligation — the proposal calls the whole package clarifying and non-substantive. But a few cleanup items are worth a specifier's attention. The proposal repeals two informational footnotes under Table 5.409.3, because some users were reading them as an instruction to multiply the listed GWP limits by 175 percent. They aren't. It also corrects the flat-glass unit in that table from "kg CO2e/MT" to "MT CO2e/MT," a printed typo. And the old January 1, 2026 sunset language is slated for repeal, since that date will have passed before the supplement is even effective.

What to do with this

Two takeaways. First: stop bracing for a big 2027 change. By statute, this supplement can't carry one. Second, narrower: if you cite CALGreen embodied-carbon sections — in specs, submittal narratives, or compliance worksheets — expect the numbers to move. A reference to "§5.409, Life Cycle Assessment," or to a §5.105 reuse provision, may point at a renamed or renumbered section once the supplement publishes.

It's still proposed, so don't rewrite anything yet. When the Commission acts in late August and the supplement is published, confirm the final section numbers — and, as always, verify against the edition your jurisdiction has actually adopted before you rely on a cite.

What CrossBeam does with it

CrossBeam reads plans against the code text that's actually in force and tracks what's coming next, so a CALGreen embodied-carbon citation resolves to the right section whether or not it moved. When the 2027 supplement lands, the renamed Section 5.409 and its reorganized options are already mapped — no stale cross-reference left in a review.