Why insurers care about Class A specifically
Class A roof assemblies paired with ember-resistant vents materially improve the building envelope's resistance to wildfire ember exposure — IBHS and NIST post-fire investigations of the 2017 Tubbs Fire and 2018 Camp Fire identified roof assembly and vent components as primary determinants of structure survival in the WUI. California's Safer From Wildfires regulation (CCR §2644.9) requires admitted insurers to recognize these mitigations in their rating plans.
California insurers run wildfire-risk models on every neighborhood in a CalFire severity zone — the probability of total-loss claims drives both pricing and underwriting decisions. A Class A roof substantially reduces modeled risk versus a non-rated assembly. Under CCR §2644.9 the actuarial benefit translates into mandatory rating-plan recognition: a Class A roof and ember-resistant vents are two of the dozen mitigation factors insurers must reflect.
