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Standards / ASTM E108 / UL 790
ASTM E108 and UL 790 roof classification
Fire-test methods for roof coverings applied as intended on a tested deck. Class A, B, and C attach to that covering-on-deck, not to shingles in a bag.
Covers: Relative fire characteristics of roof coverings on combustible or noncombustible decks under intermittent-flame, spread-of-flame, and burning-brand exposure.
Does not cover: A bag of shingles with no named deck, interior fire resistance (ASTM E119 / UL 263), vent ember intrusion, siding, or a permit.
ASTM E108 and UL 790 are test methods for roof coverings. Both titles say that. The covering is applied as intended on a combustible or noncombustible deck. Class A, Class B, and C describe how that covering-on-that-deck behaved under the fire exposures in the method. Class A is the most severe test exposure.
The class does not live in a bag of shingles. It also is not “only an assembly rating” as a slogan that contradicts the title. Codes such as CWUIC 504.2 then require a Class A roof assembly tested to these methods. Write the covering, the deck, and any named underlayment.
See roofing and Class A covering is not a bag of shingles.
Why it matters
CAL FIRE calls the roof the most vulnerable part of the home. Embers land in valleys, against walls, and in debris. Wood shake and wood shingle roofs are the wildfire non-example.
A warehouse label that says Class A does not name your plywood thickness. The building official stamps what is on the drawing.
How the tests work
ASTM E108-24 is Standard Test Methods for Fire Tests of Roof Coverings. This page quotes that public scope. ASTM’s store also listed a 2025 edition as active. Buy or read the edition the report names.
The method measures relative fire characteristics of roof coverings exposed to simulated fire sources originating outside the building. It applies when the covering is applied as intended on either a combustible or a noncombustible roof deck. The included methods are:
- Intermittent flame exposure
- Spread of flame
- Burning brand
- Flying brand
- Rain test
Three classes of fire-test exposure:
| Class | What ASTM’s scope says the covering is expected to do |
|---|---|
| A | Effective against severe fire exposure. High degree of fire protection to the roof deck. Does not slip. Not expected to present a flying-brand hazard. |
| B | Moderate fire exposure. Moderate protection to the roof deck. |
| C | Light fire exposure. Light protection to the roof deck. |
The methods also look at surface spread of flame and whether fire penetrates from the exterior to the underside of the deck under the stated exposure. They do not measure interior-origin fire resistance. That is a different test (ASTM E119 / UL 263). They do not, by themselves, complete a fire-hazard assessment of the product on your lot.
UL 790 is the parallel UL method, same job: fire tests of roof coverings on combustible or noncombustible decks when applied as intended. Ninth edition dated 18 February 2022. Codes name ASTM E108 or UL 790.
Slope, fastening, underlayment, and deck species belong in the specimen when they represent the product as installed. A granule mix in a bundle is not the specimen.
The paths that use the class
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The method as written. A lab result for a covering applied on a named deck. Manufacturer “Class A shingles” copy is not a listing.
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California CWUIC 504.2, mapped fire hazard areas. Class A roof assembly tested to E108 or UL 790. Named exceptions treat some masonry, metal, tile, and slate assemblies as Class A without that test. People still search Chapter 7A. The live book is CWUIC.
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Oregon R327, where adopted. Floor is a Class B-rated roof assembly equivalent. Wood shakes and wood shingles are not permitted. Profile gaps between covering and deck must be closed, fireblocked, or covered with ASTM D3909 72-pound cap sheet (amendment PDF). IBHS and some HOAs still ask for Class A. Spec the stricter roof if you need both.
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OSFM category 8180. Non-wood roof covering and assemblies. Handbook rows name E108 or UL 790. Listing is voluntary for most WUI products. Some 8180 rows are visible coverings. Some are underlayments that sit in a named Class A system. Owens Corning Titanium FR (8180-2372:0001) is an underlayment, not a finished roof. Two Metal Sales Image II records are the same covering family on different decks: 8180-2299:0500 names 15/32 inch plywood, felt, and two layers of VersaShield. 8180-2299:0501 names 7/16 inch OSB and DensDeck. Confirm the live GOVmotus search. That URL is a search box, not a per-record permalink.
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Insurer extras. IBHS Wildfire Prepared Essential asks for a Class A fire-rated roof covering. Safer from Wildfires names a Class A covering among California insurance-credit measures. Neither is this test method.
What people mix up
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Writing “Class A shingles” as if the class lived only in the granule.
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Saying “Class A is only an assembly rating” as an absolute that erases E108’s title. The accurate object is covering-on-the-tested-deck. Codes may then call the required result a roof assembly class.
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Treating an E84 flame-spread index as a Class A roof. ASTM E84 is a tunnel test of a specimen. Different method.
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Treating metal, tile, or “Class A underlayment” as a finished roof by itself.
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Telling an Oregon official that R327 requires Class A. The floor is Class B equivalent.
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Treating an 8180 listing as a permit, or treating absence from the handbook as a ban.
How to check
Read the adopted code for the lot. If you claim Class A or Class B, the report has to name E108 or UL 790, the class, the covering, the deck, the slope, and any required underlayment.
If you spec an OSFM 8180 model, open the product page, then search GOVmotus for that listing ID. Match the model. Put covering, deck, and ID on the drawings. How to read a listing. Deschutes County wants handbook products on the drawings.
Walk the roof. Debris in valleys and gutters is an ember bed. Cleaning is maintenance. It does not change the class.
Limits
This page does not host the ASTM or UL text. It does not decide what your building official will stamp. It does not make the house fireproof. It does not rank brands. ASTM states the methods do not, by themselves, complete a fire-hazard assessment.
FireApproved is not a listing body and not an AHJ.
Related records
Category: roofing. Guides: covering versus assembly, Class A covering is not a bag, R327 versus CWUIC.
Sources
- ASTM E108-24 Standard Test Methods for Fire Tests of Roof Coverings (ASTM International)
- UL 790 Ed. 9-2022, Standard Test Methods for Fire Tests of Roof Coverings (UL / ANSI webstore catalog for the 18 February 2022 edition)
- 2025 California Wildland-Urban Interface Code (ICC / California; 504.2)
- 2023 ORSC Section R327 amendment (Oregon Building Codes Division)
- OSFM Building Materials Listing and WUI handbook (CAL FIRE OSFM; category 8180)
- OSFM BML search (GOVmotus) (CAL FIRE OSFM; search form)
- Fire Hardening Requirements (R327) (Deschutes County)
- Home Hardening (CAL FIRE)
- Wildfire Prepared Home (IBHS)
Is Class A the shingle in the bag?
No. ASTM E108 and UL 790 are fire tests of roof coverings applied as intended on a deck. Class A, B, and C describe that covering-on-the-tested-deck. Change the deck or skip the named underlayment and you do not have that class.
Is Class A only an assembly rating?
Do not stop at that slogan. The methods are titled fire tests of roof coverings. Codes often then require a Class A roof assembly tested to those methods. The class still is not “shingles in a bag.” It is the covering on the deck as tested.
Is Class A always required in WUI zones?
No. California CWUIC 504.2 commonly requires Class A. Oregon R327, where adopted, uses a Class B floor and bans wood shakes. IBHS Essential specifies Class A. Read the adopted code and the insurer checklist separately.
Are metal roofs automatically Class A?
No. Some metal systems are Class A coverings on a named deck. Some are not. Ask for the E108 or UL 790 result and the deck. Two Metal Sales Image II rows on this site name different decks for the same covering family.