Is aluminum noncombustible? What the E136 tests show

Aluminum does melt, at about 660 C (1220 F), and that is where most of the doubt comes from. Melting and burning are separate properties, and the E136 result for an alloy does not cover a finished, coated fence panel, so ask the seller for a report on the actual product.

What does “noncombustible” mean for a Zone 0 fence?

The Board of Forestry’s rule defines noncombustible as “Materials that pass the American Society for Testing and Materials (ASTM) E136 test, thus meeting the standard for ‘noncombustible materials’ described in Section 501.4.1” of the California Wildland-Urban Interface (WUI) Code (14 CCR 1298.02(f); 1299.02(g)). The rule names no materials, aluminum included. Our guide to what counts as noncombustible covers the definition and the test in full.

The rule is adopted but not in force. The Board withdrew it from the Office of Administrative Law on 8 September 2026 (file 2026-0828-03E), and on 10 November 2026 OAL had no Board of Forestry rule under review.

Did aluminum pass the ASTM E136 test?

Yes, according to the Aluminum Association’s paper “Fire Safety of Aluminum and Its Alloys” (undated; accessed 10 November 2026). The Association commissioned two rounds of E136 testing:

The paper reports: “All of the alloys tested met the required criteria for passing the test.” It says the 2020 alloys were chosen “for their widespread use in construction.”

E136 holds samples in a 750 C (1382 F) furnace for up to 30 minutes and checks whether they raise the furnace temperature or flame. A sample can lose its shape and still pass, since the criteria cover temperature rise and flaming only.

Two limits on that result. The Aluminum Association is a trade group, and its paper links to the full results rather than reprinting them. And a test of an alloy is not a test of a finished fence panel with its coating, fasteners and inserts.

Why do people think aluminum burns?

The paper traces the belief to a few well-known events: house fires from 1960s and 1970s aluminum wiring (caused by loose connections heating plastic insulation), naval fires where aluminum parts melted, and building fires involving aluminum composite cladding. The cladding panels had a polyethylene core that burned; the paper says the aluminum “would eventually melt” but “did not combust or add to the fire in any way.” It says the naval aluminum parts likewise “melted in the extreme temperatures but did not combust or otherwise contribute to the fires.”

The paper’s one exception is powder. Like most metals, finely divided aluminum can react rapidly when mixed with an oxidizer, which is why it is used in solid rocket motors and thermite. The paper says pure aluminum powder will not ignite in air on its own, and that even aluminum foil “will simply melt like solid bulk aluminum.”

Will an aluminum fence melt in a wildfire?

It can, if flames heat it long enough. The numbers:

• Unalloyed aluminum melts at about 660 C (1220 F). Most alloys “begin to lose strength at temperatures above 150°C, or 300°F” (Aluminum Association).
• USGS gives 2,200 F (about 1,200 C) as the temperature “wildfires could reach in extreme conditions” (June 2024).

The paper argues that three properties slow the heating: aluminum’s specific heat is about twice steel’s, it conducts heat away from a hot spot 3 to 6 times better than ordinary steel, and a bare surface reflects 80 to 90 percent of radiant heat. Those figures come from the trade group and describe the metal, not any tested fence design.

For Zone 0 purposes, the point is what the fence does next to the house. A wood fence that catches fire carries flame to the wall; the Board’s guidance says “Combustible fences attached to the structure create a direct path for a fire to touch the structure.” An aluminum section that sags or melts does not add fuel to that path. Fire Safe Marin lists “ready-made steel and aluminum products” as gate options, and UC ANR calls a metal gate a “safe choice.” For the temperatures in more detail and what happens to a fence near a burning house, see does aluminum melt in a wildfire.

Is aluminum or steel better for fire?

Both meet the rule’s definition. NIST’s 2022 fence report names steel with stone and brick as noncombustible fence materials, and the Aluminum Association’s tests cover aluminum. The trade group says a given mass of aluminum takes about twice as much energy as the same mass of steel to heat up by one degree, but aluminum still melts at about 660 C and most alloys lose strength above about 150 C. Our best fire resistant fence comparison weighs the two on cost, looks and upkeep.

Does the E2652 alternative work for aluminum?

No. WUI Code 501.4.1 lets a material qualify either by passing E136 or by testing under ASTM E2652 “using the acceptance criteria prescribed by ASTM E136.” The Aluminum Association says E2652’s scope states it “is not suitable or satisfactory for materials that soften, flow, melt, intumesce or otherwise separate from the measuring thermocouple,” so it “is therefore not applicable to aluminum.” The paper adds: “E136 has no such issue.” If a seller shows you an E2652 report for an aluminum product, ask why.

Does powder coating change the answer?

It can still qualify through an exception in the WUI Code. Section 501.4.1 accepts as noncombustible a material with “a structural base of noncombustible material” and “a surfacing of not more than 0.125 inch (3.18 mm) in thickness having a flame spread index not greater than 50” under ASTM E84 or UL 723.

In our reading, that is the clause a powder-coated aluminum fence relies on: the alloy passes E136 and the coating meets the thickness and flame spread limits. The rule does not mention coatings, and the local inspector makes the call. E84 on its own cannot prove noncombustibility; the Aluminum Association notes its scope calls it “unsuitable for determining the combustibility or noncombustibility of a material.” It only covers the coating half of the exception.

Wood-grain finishes need the same check: a wood-look film or printed coating is still a surfacing that needs an E84 result. Any plastic or composite insert is a separate material and would have to pass E136 on its own.

What should I ask an aluminum fence seller for?

Before buying a panel or gate for the first 5 feet at the house, ask for:

1. An ASTM E136 report naming the alloy used in the posts, rails and pickets or slats. An industry paper about alloys in general does not cover the specific product.
2. An ASTM E84 or UL 723 flame spread result for the coating, with its thickness, so the 501.4.1 exception can be checked.
3. A parts list showing that hinges, latches, post caps and inserts are metal, and that no wood post is needed at the wall.

No state approval or listing program for Zone 0 products exists, so “Zone 0 approved” on a product page refers to no state approval. None of the seven fence sellers and sites we reviewed in November 2026 published an E136 report for a specific product. For how this applies to the gate itself, see Zone 0 gate requirements.