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Standards / SFM 12-7A-4
SFM 12-7A-4 decking
SFM 12-7A-4 is the California State Fire Marshal test method for deck walking surfaces in wildland-urban interface construction. The method is a two-part laboratory test of a deck assembly: under-deck flame, then a burning brand on the boards. OSFM handbook category 8110 lists models tested to 12-7A-4 or the 12-7A-4A alternate. It is not Oregon R327, not under-deck mesh, and not a permit.
Covers: Under-deck flame and burning-brand performance of exterior deck walking-surface assemblies.
Does not cover: The 12-7A-4A under-deck-only alternate treated as the two-part method, Oregon R327 walking-surface tests, under-deck enclosure, or a permit.
SFM 12-7A-4 is the California test method for deck walking surfaces in WUI construction. It lives in the California Referenced Standards Code, Title 24 Part 12, Chapter 12-7A. OSFM handbook category 8110 is the listing bucket that uses this method and the 12-7A-4A alternate.
Homeowners search “WUI decking” and “Trex banned.” This page keeps the California walking-surface test distinct from 12-7A-4A, from Oregon R327, and from the space under the boards. See wildfire decking.
Why it matters
Embers land on boards, lodge in gaps, and fall through to joists and stored fuel. Flame then sits under the walking surface and against the wall. A board that resists ignition in the lab is not an empty crawlspace and is not Zone 0.
A pass is a result for that assembly, as built for the test. It is not a permit. The listing body, the adopted code, and the authority having jurisdiction (AHJ) are separate steps. Read how to read a listing.
How the test works
12-7A-4 is a two-part laboratory procedure on a small deck specimen.
- Part A, under-deck flame. An 80 kW burner sits under the specimen for three minutes. The lab records heat release and watches whether the assembly keeps flaming or dropping burning particles through a 40-minute observation.
- Part B, burning brand. A Class A size roof-test brand is placed on the walking surface in a 12 mph wind. Observation again runs until combustion ends, or 40 minutes.
A pass means that specimen met those conditions. It does not name your joist species, gap, fasteners, or wall unless the later listing does.
Sibling Chapter 12-7A methods cover other assemblies: 12-7A-1 siding and sheathing, 12-7A-2 windows, 12-7A-3 eave and horizontal-projection underside. Do not import those results onto a deck board.
12-7A-4 versus 12-7A-4A
| Method | What the lab does | What it is not |
|---|---|---|
| SFM 12-7A-4 | Under-deck flame and a burning brand on the boards | An OSFM listing, a permit, or Oregon R327 |
| SFM 12-7A-4A | Under-deck heat-release alternate only | The two-part 12-7A-4 method |
The 2 September 2025 OSFM handbook names both methods in the category 8110 header. The ingested 8110 rows on this site record 12-7A-4A as the test protocol. Confirm the live GOVmotus record before you spec.
Many 12-7A-4A listings add a wall-covering condition. Trex Transcend 8110-2052:0004 notes that ASTM E84 was not conducted and that the attached exterior wall covering shall be noncombustible or ignition-resistant. That is a listing condition, not a ban.
The paths
California. CWUIC is the live book as of 1 January 2026 (people still search Chapter 7A). Walking-surface products that OSFM has listed sit in category 8110. The handbook names SFM 12-7A-4 and 12-7A-4A as the test methods for that bucket. Listing is still voluntary for most WUI products. Unlisted materials can meet a prescriptive path if the building official agrees. See CWUIC and OSFM BML.
Oregon R327, where adopted, does not use SFM 12-7A-4. Walking surfaces more than 30 inches and less than 12 feet above grade follow R327.3.5 (amendment PDF): ASTM E2632 and E2726, ignition-resistant material, exterior fire-retardant-treated wood, noncombustible material, or E2632 where the wall covering is noncombustible or ignition-resistant. An 8110 listing is not, by itself, a checked box for R327.3.5. Read R327 versus CWUIC and wildfire decking.
Under-deck is a different rule. California and Oregon both treat the opening to grade as enclosure or protection, not as this walking-surface method. IBHS Wildfire Prepared and CAL FIRE home hardening put the under-deck footprint in the ember-resistant zone. If you screen, close the vertical plane to grade. Horizontal mesh under the boards is the installation mistake in Findings.
What people mix up
- Treating 12-7A-4 and 12-7A-4A as the same test.
- Treating an OSFM 8110 listing as an R327 walking-surface pass, or treating R327 as Chapter 7A.
- Treating “composite” as a fire class. Composite is a material family. The listing is a model.
- Calling a flame-spread class on a board a Class A roof. Roof class is ASTM E108 or UL 790 on a roof assembly. Part B’s Class A brand is a firebrand size.
- Assuming all wood decks are illegal. Solid wood appears in category 8110, including American Wood Council 8110-2041:0002. Assuming all wood is legal is the other error.
- Saying Trex is banned. Named Trex models are in the handbook. The listing notes still apply.
- Stapling mesh under the boards and leaving the sides open.
- Treating a listed board as the complete deck specification.
How to check
Read the adopted code for the lot. If none, you are in voluntary hardening or an insurer checklist.
On the listing: program, listing ID, URL, test protocol (12-7A-4 or 12-7A-4A), and any wall-covering, joist, gap, or E84 note. Confirm the model on the drawing is the model on the listing. Search GOVmotus. Do not spec from a screenshot.
Examples of 8110 records on this site: AZEK Vintage 8110-2042:0001, Trex Transcend 8110-2052:0004, American Wood Council 8110-2041:0002. Confirm the live record before you spec.
Deschutes County’s R327 page says handbook products count only if you show them on the drawings. See show the product on the drawings. The building official still stamps the permit.
On the house: walking-surface height, what is stored underneath, whether any screen is vertical to grade or horizontal under the boards.
Limits of this page
This page does not decide what your building official will stamp. It does not rate rot, snow, or railing structure. It does not write a stair rule. It does not make the house fireproof. Absence from the OSFM handbook is not an automatic ban. Presence is not an automatic permit.
Related records
- Wildfire decking
- Under-deck mesh belongs on the vertical plane
- OSFM Building Materials Listing
- California Wildland-Urban Interface Code
- Chapter 7A (historical name)
Sources
- California Referenced Standards Code, Chapter 12-7A (ICC / California, 2022)
- OSFM Building Materials Listing (CAL FIRE OSFM; 2025 WUI handbook dated 2 September 2025)
- OSFM BML search (GOVmotus)
- 2025 California Wildland-Urban Interface Code
- 2023 ORSC Section R327 amendment
- Fire Hardening Requirements (R327) (Deschutes County)
- Home Hardening (CAL FIRE)
- Wildfire Prepared Home (IBHS)
Is SFM 12-7A-4 the same as 12-7A-4A?
No. 12-7A-4 is a two-part test of a deck assembly, under-deck flame plus a burning brand on the walking surface. 12-7A-4A is the under-deck heat-release alternate. OSFM category 8110 names both. Read the listing test protocol, not the category header alone.
Does an OSFM 8110 listing mean I can install that deck in Oregon?
No. An 8110 listing is a California Building Materials Listing record for a named model. Oregon R327, where adopted, uses different walking-surface tests. Deschutes County will accept handbook products when they are shown on the drawings. Confirm with the building official.
Does a listed board finish the deck?
No. Passing SFM 12-7A-4 or 12-7A-4A is a walking-surface result. It does not enclose the underfloor, empty stored fuel, or place mesh on the vertical plane to grade.
Is the Class A brand in 12-7A-4 a Class A roof?
No. Part B uses a Class A size burning brand from the roof-test apparatus. That is a firebrand size, not an ASTM E108 Class A roof-assembly rating for the deck.