Does Brookfield, WI need an earthquake retrofit?

Under the seismic model IBC and ASCE 7 use for new construction, Brookfield is Category B. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Brookfield in the 19th percentile nationally for seismic hazard - higher than 19% of the 4,875 US cities USGS was checked against here.

Brookfield by the numbers

The raw figures: peak ground acceleration 0.036g, short-period spectral response 0.075g, 1-second spectral response 0.048g. Among 157 Wisconsin cities in this dataset, Brookfield ranks 53 for seismic hazard, the 67th percentile within the state. About 41,268 people live in Brookfield, Wisconsin.

Retrofit economics for Brookfield

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

Insuring against this, not just retrofitting

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 Brookfield address.

More on how this number was built

The methodology guide covers exactly how USGS's public design-maps API produced Brookfield'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.