Ember-resistant vents and eaves: the wildfire tests the code just edited
ASTM E2886 (vents) and E2957 (eaves) were amended in the January 2026 CRC errata — here's what each test actually checks.
The chapter nobody reads got two real edits
Most people skip Chapter 44. It's the referenced-standards list — the back-of-the-book index of every ASTM, ANSI and NFPA standard the code leans on. But the January 2026 errata to the 2025 California Residential Code (Item No. 5525S251) reached into that chapter and amended two standards that govern home hardening in a Fire Hazard Severity Zone: ASTM E2886/E2886M—2014 (exterior vents) and ASTM E2957—2015 (eaves, soffits and other projections).
These aren't obscure. They're the test backbones for deciding whether a vent or a boxed-in eave assembly is legal where embers fly.
Verified against the 2025 CRC Part 2.5 errata, page 44-13, and the Chapter 44 referenced-standards text — both carry the amended ASTM E2886 and E2957 entries, with the cited editions, verbatim.
E2886: the ember-and-flame test for vents
ASTM E2886 is the vent test. It evaluates whether a gable, foundation, soffit or under-eave vent can resist the entry of embers and direct flame. In the CRC's referenced-standards list it's tied to R337.6.2 and R337.6.3.
Here's the thing about what the test actually decides: the pass/fail criteria don't live in the ASTM standard — they live in the WUI Code. Section 504.10.1 says ventilation openings must be covered with State Fire Marshal–listed or WUI vents tested to ASTM E2886, meeting all three of these: no flaming ignition of the cotton during the Ember Intrusion Test; no flaming ignition during the Integrity Test portion of the Flame Intrusion Test; and a maximum unexposed-side temperature of 662°F (350°C).
What the errata changed is narrower, and it's about reporting. It revised E2886 Sections 10.1.8.3, 10.1.8.4 and 10.1.8.5 so that the optional Insulation Test of the Flame Intrusion Test now reports the unexposed-side temperatures, the single highest thermocouple reading and the highest average across all the thermocouples. In plain terms: better data on how hot the inside face of a vent gets.
E2957: the eave-and-soffit test, now with a retry
ASTM E2957 is the eaves test — it measures whether an eave overhang, soffit or cantilevered projection resists fire penetration from underneath. It's cited at R337.7.5, R337.7.6, R337.7.8 and R337.7.10. Note the division of labor in the code's referenced-standards list: vents run on E2886 (R337.6); eaves and projections run on E2957 (R337.7).
The errata added a new Section 12.5, "Conditions of Acceptance." The substance: a product is tested on three specimens, and should one of the three fail, three additional tests may be run — and all of them must meet the conditions of acceptance. Those conditions are: no flame penetration of the eaves or horizontal projection assembly at any time; no structural failure at any time; and no sustained combustion of any kind at the conclusion of the 40-minute test.
If that sounds familiar, it should. It's the same 3-plus-3 rule already written into the WUI Code at Section 504.7.2 — same three conditions, same retry logic. The standard is just syncing to the requirement builders and listing agencies already build to. And it's the exact test that Section 504.3, Item 6 points to when it lets a boxed-in roof eave soffit assembly serve as enclosed-eave protection.
Why this matters at the counter
If you specify a listed ember-resistant vent or a boxed-eave assembly, this is your paper trail. The product's listing traces back to an E2886 or E2957 report, and that report has to meet the standard the code actually names. For residential work, Chapter 44 references the 2014 edition of E2886 and the 2015 edition of E2957 — that's the edition a reviewer should be checking a listing against.
One caveat worth flagging: Part 7, the California Wildland-Urban Interface Code, references newer editions — E2886/E2886M—2020 and E2957—2017. Two code parts, two edition years, both legitimate. Don't assume the residential citation and the WUI citation point at the same printing of the standard. When the stakes are a fire-zone approval, check the edition against the specific part you're working under, and confirm listing acceptance with your local jurisdiction.
What CrossBeam does with it
CrossBeam tells you which test standard — and which edition — a vent or eave assembly has to meet for the code part you're actually building under, and flags it when the residential and WUI citations diverge. It turns a buried referenced-standards edit into a plain answer you can drop into a correction letter or a submittal review.