Ferndale's Seismic Design Category, explained

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Ferndale in Seismic Design Category D: High seismic hazard - this is the category most of coastal California, the Pacific Northwest, and other active fault regions fall into. Code mandates significant seismic detailing and restricts irregular structural configurations. This is the category the Brace + Bolt scope (cripple-wall bracing, foundation bolting) is built for. Rank it against the rest of the country and Ferndale sits at the 88th percentile for seismic hazard among 4,875 US cities.

Ferndale by the numbers

The raw figures: peak ground acceleration 0.43g, short-period spectral response 1.002g, 1-second spectral response 0.351g. Among 125 Washington cities in this dataset, Ferndale ranks 81 for seismic hazard, the 35th percentile within the state. About 16,706 people live in Ferndale, Washington.

Retrofit economics for Ferndale

Outside California, no state-level retrofit grant equivalent to Brace + Bolt could be found for Washington. A typical retrofit still runs $5,000-$10,000 nationally, about $7,000 for a common single-family job.

What this means for insurance

Outside California, earthquake coverage is typically sold as an endorsement added to a standard homeowners policy, not a separate product - worth asking about directly when getting a home-insurance quote for a Ferndale address.

More on how this number was built

The methodology guide covers exactly how USGS's public design-maps API produced Ferndale's numbers. The guide to what a Seismic Design Category actually means covers why a category is never a substitute for an engineer's assessment of one specific house.