Ignition-resistant versus noncombustible

Ignition-resistant is not ASTM E136. Oregon R327, where adopted, defines ignition-resistant material as an exterior product tested to ASTM E84 or UL 723 for 30 minutes, with a flame spread index not more than 25 and named extra conditions. Noncombustible is ASTM E136. OSFM category 8170 is ignition-resistant materials. Category 8175 is the E136 bucket. A fiber-cement brand is not automatically either.

You are specifying wall covering. Ignition-resistant is an extended flame-spread run. Noncombustible is ASTM E136. They are not two names for Hardie.

Why it matters

Embers collect at the wall base, at roof-to-wall joints, and against anything that touches the covering. CAL FIRE’s home-hardening page says combustible siding, once ignited, can carry flame to windows, eaves, and vents. Codes and insurer checklists then ask for ignition-resistant or noncombustible covering. Those are different test methods. If you treat them as synonyms, you will spec the wrong board.

How the two tests work

Ignition-resistant, Oregon definition. ASTM E84 is a Steiner tunnel. The published method is a 10-minute run. It reports a flame spread index and a smoke developed index. ASTM states that a flame spread index by itself does not classify a material as noncombustible. Where R327 is adopted, ignition-resistant material is that tunnel, or UL 723, extended to 30 minutes, flame spread index not more than 25, no significant progressive combustion, and a flame front not more than 10.5 feet beyond the burner centerline (amendment PDF). Read ASTM E84 for the 10-minute versus 30-minute split.

Noncombustible. ASTM E136 heats a small specimen in a 750 °C vertical tube furnace. Codes typically treat a pass as noncombustible. Limited flaming is still allowed. The method does not test the wall as built. It does not apply to laminated or coated materials. Read ASTM E136.

Do not collapse these into one stamp.

The paths

1. Prescriptive wall covering, Oregon R327 where adopted. Exterior walls may be noncombustible, ignition-resistant, heavy timber, or log (amendment PDF). Pick the word the code named. Writing “fire-rated Hardie” is not a path.

2. Deemed-to-comply, same section. One layer of 5/8 inch Type X exterior gypsum sheathing behind the cladding, or the exterior portion of a 1-hour fire-resistance-rated exterior wall assembly. The gypsum is part of the assembly. It is not an E136 pass for the visible board. See Type X behind the covering.

3. Performance path wall, Oregon. A wall assembly tested to ASTM E2707 for a 10-minute direct-flame exposure, with the conditions in R327.3.3.2. That is not E84 and not E136.

4. Same two words, other assemblies. R327 uses ignition-resistant and noncombustible again on eaves and projections, and on decking walking surfaces. A wall covering class does not finish the eave or the deck.

5. California listing buckets. CWUIC is the live California WUI book as of 1 January 2026. People still search Chapter 7A. OSFM category 8170 is ignition-resistant materials. Category 8175 is noncombustible materials. Category 8140 is exterior wall siding and sheathing. Many 8140 rows name SFM 12-7A-1, a direct-flame wall-assembly method. Some 8140 rows name E136 instead. Some name an extended E84 run and “Ignition resistant.” Listing remains voluntary for most WUI products. Absence from the handbook is not an automatic ban. Presence is not an automatic permit. See OSFM BML.

6. Insurer extras. IBHS Wildfire Prepared Essential does not require noncombustible wall covering. Enhanced does. That is a designation, not adopted code. It is not Oregon ignition-resistant material. See IBHS does not replace adopted code.

Oregon and California are not the same job. Read R327 versus CWUIC.

What people mix up

• Calling ignition-resistant the same thing as noncombustible. They are different tests and different OSFM categories.

• Treating a 10-minute flame spread index of 25 as Oregon ignition-resistant. R327 extends the run to 30 minutes and adds the progressive-combustion and 10.5-foot flame-front conditions.

• Treating an OSFM 8170 “extended 20-minute” note as Oregon’s 30-minute definition. Nichiha AWP (8170-2029:0005) is an 8170 record whose ingested handbook note names ASTM E84 with an extended 20-minute run. Confirm the live GOVmotus record. Do not import that note into an R327.2 check.

• Treating category 8170, 8175, and 8140 as one bucket. 8170 is ignition-resistant materials. 8175 is noncombustible. 8140 is exterior wall siding and sheathing.

• Calling every fiber-cement product noncombustible. Hardie Textured Panel (8140-2026:0502) carries a handbook note of ASTM E136 and a noncombustible rating. HardiePlank and HardiePanel (8140-2026:0005) is an 8140 record without that E136 rating on the handbook line we ingested.

• Treating every metal panel as 8175. TruLog Siding (8170-2399:0001) is steel siding in 8170 with an E84 note. Clicklad aluminum (8175-2405:0001) is an 8175 E136 row. Read the category.

• Treating a brand as a listing. The listing is a model, thickness, and often a substrate. “Hardie” is not an ID.

• Painting a fire coating on wood siding and calling it ignition-resistant or noncombustible. Coatings are not on the R327 wall list. ASTM E136 does not apply to coated materials. See Findings.

• Calling an E84 result Class A. On this site Class A is a roof-assembly class under ASTM E108 or UL 790.

• Reading Type X gypsum behind cladding as an E136 pass for the visible board. Type X is a deemed-to-comply assembly path.

• Treating SFM 12-7A-1 as ASTM E84. 12-7A-1 is a direct-flame wall-assembly method. Oregon’s performance wall path names ASTM E2707, not 12-7A-1.

• Treating IBHS Enhanced noncombustible wall covering as Oregon ignition-resistant material.

• Treating a six-inch noncombustible wall base, or Zone 0 gravel, as a wall covering class. Those are different recipes. Mesh that is metal is a material recipe for vents. It is not an E136 listing.

• Reading “OSFM listed” as an Oregon permit. Deschutes County will use the handbook when the product is on the drawings. The building official still stamps the job. Show the product on the drawings.

How to check

1. Read the adopted code for the lot. If none, you are in voluntary hardening or an insurer checklist.

2. If R327 applies and you claim ignition-resistant material, the report has to match R327.2: ASTM E84 or UL 723, 30 minutes, flame spread index not more than 25, no significant progressive combustion, flame front not more than 10.5 feet beyond the burner centerline.

3. If you claim noncombustible, the definition is ASTM E136. An E84 number is not that pass.

4. If you spec an OSFM listed model, open the product page, then the listing URL. Match the listing ID and the model. Read the category (8170, 8175, or 8140) and the protocol. How to read a listing.

5. Search the live OSFM BML record. Do not spec from a screenshot. Listings change.

6. Put the manufacturer, model, and listing program on the drawing. Deschutes County says handbook products count only if you show them on the drawings.

Limits

This page does not decide what your building official will stamp. It does not make the house fireproof. It does not rank brands. It does not turn an 8170, 8175, or 8140 table into a shopping list.

It does not replace the ASTM E84, ASTM E136, ASTM E2707, or SFM 12-7A-1 pages. Those methods still do different jobs.

R327, where adopted, is a new-construction code with replacement and addition rules that the local department interprets. FireApproved is not a listing body and not an AHJ.

Related records

• Siding, eaves, decking
• ASTM E84, ASTM E136, ASTM E2707, SFM 12-7A-1
• OSFM Building Materials Listing
• Oregon R327 versus California CWUIC
• How to read a listing
• Coatings are not an R327 wall path

Examples on this site

Confirm the live GOVmotus record before specification. This table is not a complete catalog.