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A Class A rating is not a service-life clock
A Class A letter is a lab result on a tested covering-on-deck, not a calendar. ASTM E108 or UL 790 do not print a year when the class expires. IBHS Base still wants that covering kept clear of debris. FEMA P-737 says not to assume existing asphalt still meets Class A. Where Oregon R327 is adopted, the floor is a Class B-rated assembly equivalent.
You are looking at a 20-year roof with needles in the valley and a faded Class A bag in the garage. The bag is not the roof.
CMP-005 is still brief. See covering versus assembly. Do not use a house-level hub graphic as a weathering clock.
Why it matters
Embers ignite debris on a rated roof. IBHS scores the covering you have, kept clean. A listing from 2018 does not mow your gutters.
How the documents split
| Document | What it scores | What it does not score |
|---|---|---|
| E108 / UL 790 | Assembly in the lab | Moss, age, debris |
| IBHS Base | Class A covering plus kept clear | A year-count |
| FEMA | New asphalt can meet Class A. Do not assume existing does | A permit |
| R327.3 | Class B-rated assembly equivalent. No wood shakes | Class A forever |
The paths
1. New roof. Write the assembly. See how to read a Class A roof listing.
2. Existing roof. FEMA. Do not assume the old shingles still test Class A. Clean debris if you are scoring IBHS.
3. Oregon. Class B floor. Spec Class A if IBHS or an HOA wants it too.
4. Edges. Bird stops and valleys are separate. See tile bird stops.
What people mix up
- A bag date as a class expiration.
- Dirty Class A as IBHS-complete.
- Oregon requiring Class A.
How to check
- What assembly is on the roof now, not what was ordered.
- Is the covering clear of debris.
- Which document you are scoring.
Limits
This page does not invent a 20-year rule. FireApproved is not the AHJ.
Related records
Questions
When does a Class A roof stop being Class A?
The test classifies the assembly as built and tested. This page does not invent an expiration year. IBHS still requires the covering to stay clear of debris. FEMA says not to assume existing asphalt shingles meet Class A. Confirm the live listing and the roof you actually have.
Does moss void the class?
E108 does not score moss. IBHS Base requires the covering kept clear of vegetative debris. A dirty Class A roof fails that checklist even if the shingle bag once said Class A.
Does Oregon require Class A forever?
Where R327 is adopted, the floor is a Class B-rated assembly equivalent. Wood shakes are not permitted. IBHS Base still asks for Class A covering. Spec both if you need both.