Duvall's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Duvall is 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. Nationally, Duvall ranks above 91% of the 4,875 cities in this dataset for seismic hazard - the 91th percentile.

Duvall by the numbers

USGS's underlying values for Duvall: 0.534g peak ground acceleration, 1.244g at short period, 0.436g at 1 second. Within Washington alone, Duvall ranks 46 of 125 cities by seismic hazard - the 64th percentile in-state. Duvall has a population of about 9,176.

What a retrofit costs in Duvall

A full earthquake retrofit typically runs $5,000-$10,000 nationally (around $7,000 typical), driven mainly by house size and foundation type, not by Washington specifically. California's Earthquake Brace + Bolt grant, which covers a large share of this cost, is a California-only program and does not apply in Washington.

What this means for insurance

A Duvall homeowner cannot buy a standalone earthquake policy in most cases - it is added to an existing homeowners policy as an endorsement, so the place to start is a regular home-insurance quote.

Where Duvall's figures come from

Duvall's Category D and every number above trace to USGS's own ASCE 7-16 Design Maps service - see the methodology guide. See the category explainer for what Category D does and doesn't tell you about Duvall.