Class A fire rated siding has the lowest flame spread under ASTM E84 testing, making it the safest fire performance class. With 7,000+ installations completed, woman-owned Coastal Windows & Exteriors has served 730+ towns across Massachusetts, New Hampshire and Maine since 2011, and we’ll show you where each siding material lands on the fire-rating scale before you choose.
Class A is the top rung on a simple three-tier scale that measures how fast flame spreads across a material. The lower the score, the safer the rating. Knowing where siding lands on this scale helps you choose with confidence.
What Homeowners Need to Know:
- Top rating: Class A fire rated siding earns the lowest flame spread under ASTM E84. It marks the safest of the three fire classes.
- The scale: ASTM E84 scores flame spread from 0 to 25 for Class A. Class B runs 26 to 75, and Class C runs 76 to 200.
- Who qualifies: Fiber cement scores near zero on this scale. Many vinyl products reach Class A too, though vinyl still burns.
- The top tier: James Hardie fiber cement is non-combustible and adds no fuel. This class a siding sits at the safest end.
- Why it matters: Some insurers and local codes prefer Class A materials. The rating signals strong, tested fire performance.
Comparing Materials by Fire Class
| Option | Pros | Cons | Best For | Flame Spread |
|---|---|---|---|---|
| Fiber cement | Non-combustible, no fuel added, durable | Higher cost than vinyl | Fire-prone areas, longevity | Near zero (Class A) |
| Vinyl | Affordable, many Class A products, low upkeep | Combustible, softens in heat | Budget, broad use | Class A possible, still burns |
| Wood | Natural look, renewable | Ignites easily, spreads fire | Aesthetic-first builds | Higher class, least safe |
Choosing Class A Siding
Top Recommendation: Choose James Hardie fiber cement for non-combustible, Class A safety. Get a free estimate today.
Best for budget: Pick a Class A vinyl product when cost is top factor in your decision.
Smart for fire-prone areas: Favor non-combustible materials that score near zero.
Ready to upgrade to Class A siding? Schedule a free consultation today. Coastal Windows & Exteriors is a James Hardie Elite Preferred Contractor and the #1 woman-owned James Hardie exterior remodeling company in New England, with 7,000+ installations across MA, NH, and ME. Financing runs up to 20 years through third-party vendors, based on credit approval.
Request a free siding estimate from Coastal Windows & Exteriors.
Browse our complete siding FAQ guide from Coastal Windows & Exteriors.
Explore the Coastal Windows & Exteriors Siding Exterior Remodeling Home Improvement Help Center.
Still have questions about What is Class A fire rated siding? See the areas we serve and talk to your local siding contractor.
Last Updated: September 2026
Sources:
- Fiber cement siding averages about $21,500 installed in the US. JLC 2025 Cost vs. Value Report, New England, regional cost data for fiber cement siding replacement. (2026)
