United States / Build / Chemco Thermex-FR exterior treated redwood and western red cedar
Chemco Thermex-FR exterior treated redwood and western red cedar This is a listed siding assembly. Listing 2520-1450:0502. This site cites ASTM E84. Match the model and orientation.
Listed · limited evidence. Active CAL FIRE BML listing 2520-1450:0502, expires 2027-06-30 (verified against the live BML 2026-08-25). Limited evidence: a single positive channel so far — more programs or documentation may still move this record. This status is computed from the cited evidence by the published rule, never hand-assigned.
▲ CAL FIRE BML 2520-1450:0502 · active
CAL FIRE OSFM listing 2520-1450:0502 covers Thermex-FR exterior fire-retardant-treated redwood and western red cedar lumber. Chemco's manufacturer-hosted evaluation documents pressure- impregnated lumber for exterior wet-location use and an ASTM E84 flame-spread index of 25 or less.
Kind: listed-assembly.
Brand: Chemco, Inc. . Listing evidence: OSFM WUI handbook 2026-08-25.
Page reviewed 2026-08-25. JSON (CC BY 4.0)
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Documents for this product Each link opens the publisher's own copy, so you read the revision they are shipping today.
Documented attributes Each value below points to its field-level manufacturer, official-listing, test-report, or standard-body evidence.
Models named on the listing Model Application Thermex-FR redwood lumber Thermex-FR western red cedar lumber
Specification notes Match species, grade, dimensions, treatment plant and retention, structural design adjustments, exposure, cuts, fasteners, finishes, and every current listing and manufacturer condition. ASTM E84 describes surface burning; it is not a roof Class A rating or an hourly fire-resistance rating. Can I use this here How this product meets each requirement (30)
Requirement constraints (30)
Each table compares this product's documented attributes with one published requirement.
The comparison does not change from place to place, so it is printed once.
ORSC R327 noncombustible deck surface undocumented Field Required Documented value State Assembly role Assembly role = deck surface Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
Austin Zone A noncombustible appendage undocumented Field Required Documented value State Assembly role Assembly role is one of deck structure, deck surface Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
IWUIC Class 1 wall-base protection undocumented Field Required Documented value State Assembly role Assembly role = wall base protection Not documented undocumented Height Height ≥ 6 in Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
California SFM 12-7A-1 wall undocumented Field Required Documented value State Test standard Test standard = sfm 12 7a 1 Not documented undocumented
IWUIC Class 1–2 noncombustible deck undocumented Field Required Documented value State Assembly role Assembly role is one of deck structure, deck surface Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
Colorado CWRC Class A deck surface undocumented Field Required Documented value State Assembly role Assembly role = deck surface Not documented undocumented Fire rating Fire rating = class a Not documented undocumented
Colorado CWRC noncombustible deck structure undocumented Field Required Documented value State Assembly role Assembly role = deck structure Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
Colorado CWRC noncombustible deck surface undocumented Field Required Documented value State Assembly role Assembly role = deck surface Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
Colorado CWRC wall-base protection undocumented Field Required Documented value State Assembly role Assembly role = wall base protection Not documented undocumented Height Height ≥ 6 in Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
2018 IWUIC Class 1–2 noncombustible deck undocumented Field Required Documented value State Assembly role Assembly role is one of deck structure, deck surface Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
Kittitas IR1–IR2 noncombustible deck undocumented Field Required Documented value State Assembly role Assembly role is one of deck structure, deck surface Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
Kittitas IR1–IR2 one-hour deck undocumented Field Required Documented value State Assembly role Assembly role is one of deck structure, deck surface Not documented undocumented Fire resistance Fire resistance ≥ 60 min Not documented undocumented
Kittitas IR1 one-hour wall undocumented Field Required Documented value State Fire resistance Fire resistance ≥ 60 min Not documented undocumented
Kittitas Table 503.1 N.C. wall undocumented Field Required Documented value State Fire resistance Fire resistance ≥ 60 min Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
2021 IWUIC Class 1–2 noncombustible deck undocumented Field Required Documented value State Assembly role Assembly role is one of deck structure, deck surface Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
2006 Utah UWUI Class 1–2 noncombustible deck undocumented Field Required Documented value State Assembly role Assembly role is one of deck structure, deck surface Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
2006 Utah UWUI Class 1–2 one-hour deck undocumented Field Required Documented value State Assembly role Assembly role is one of deck structure, deck surface Not documented undocumented Fire resistance Fire resistance ≥ 60 min Not documented undocumented
2006 Utah UWUI Table 503.1 N.C. wall undocumented Field Required Documented value State Fire resistance Fire resistance ≥ 60 min Not documented undocumented Noncombustible Noncombustible = Yes Not documented undocumented
Chemco Thermex-FR exterior treated redwood and western red cedar. FireApproved. https://fireapproved.com/materials/chemco-thermex-fr-exterior-treated-redwood-cedar/. Last verified 2026-08-25. Verify at the source. Every listing number and claim here links to its origin — listings change and local amendments govern, so check the current record before you specify.