Naperville's Seismic Design Category, explained

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Naperville in Seismic Design Category B: Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. That puts Naperville in the 45th percentile nationally for seismic hazard - higher than 45% of the 4,875 US cities USGS was checked against here.

Where Naperville sits in Illinois

The raw figures: peak ground acceleration 0.07g, short-period spectral response 0.136g, 1-second spectral response 0.067g. Among 330 Illinois cities in this dataset, Naperville ranks 89 for seismic hazard, the 73th percentile within the state. About 153,124 people live in Naperville, Illinois.

Retrofit economics for Naperville

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

Earthquake insurance for a Naperville home

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 Naperville address.

More on how this number was built

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