The challenge
Wind-blown embers ignite homes through roofs, vents and siding, letting wildfires spread house to house.
The case
After the 1991 Oakland Hills firestorm, California tightened rules for homes in fire-prone areas, culminating in the Chapter 7A building code that took full effect in 2008. It sets standards for ember-resistant vents, roofs, exterior walls and windows. Economists Patrick Baylis and Judson Boomhower studied damage records for most US homes exposed to wildfires since 2000. A California home built in 2008 or later was about 16 percentage points, or 40%, less likely to be destroyed than a 1990 home facing the same fire. Nearby older homes were also slightly safer. A separate study of the 2018 Camp Fire found newer homes survived more often but did not find a clear jump at the 2008 cut-off.
Why it worked
Mandatory standards at the point of construction protected far more homes than the voluntary approaches used in other states. Each fire-resistant home also helps protect its neighbours.
Sources
- Baylis, P. & Boomhower, J. (2021). Mandated vs. Voluntary Adaptation to Natural Disasters: The Case of U.S. Wildfires. NBER Working Paper 29621.
- Knapp, E. E. et al. (2021). Housing arrangement and vegetation factors associated with single-family home survival in the 2018 Camp Fire, California. Fire Ecology.
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