All structures MUST be hardened for ember exposures.
Research and experience from past WUI fires shows that a majority of structures are ignited by embers. The widespread and unpredictable nature of ember showers means that all structures need to be protected against ember ignitions.
HMM recommends addressing all vulnerabilities unique to each structure. Forty vulnerabilities to ember ignition, and their mitigating actions, have been identified in Table A. Steps should be taken to further mitigate any additional vulnerabilities that may be identified on individual structures.