Which statement best describes Class 'B' fire-resistance rating for roofing?

• A. Fire-resistance rating indicating roofing materials withstand moderate exposure to fire from outside; not available for asphalt shingles.
• B. The highest fire-resistance rating and applies to all roof types.
• C. Fire-resistance rating indicating roofing materials withstand light exposure to fire from outside.
• D. No rating exists for this material.

Answer: (A)

Class B describes a middle level of exterior-fire resistance for a roofing assembly. It means the roof can withstand a moderate exposure to fire from outside, sitting between the strongest rating (Class A) and the weakest common rating (Class C). This rating comes from standardized tests and helps determine how well a roof resists flame spread from outside, which influences code requirements and safety decisions. In practice, asphalt shingles are often Class A, though some products can carry B or C ratings depending on their construction, so the idea that there is no Class B rating for asphalt shingles isn’t universally true. The other statements would describe either the highest rating, the lowest/least resistance, or no rating at all, none of which match the concept of a mid-range exterior-fire resistance level.