Carol Stream's Seismic Design Category, explained

Carol Stream carries Seismic Design Category B under USGS's ASCE 7-16 model. Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. Nationally, Carol Stream ranks above 42% of the 4,875 cities in this dataset for seismic hazard - the 42th percentile.

Where Carol Stream sits in Illinois

The raw figures: peak ground acceleration 0.066g, short-period spectral response 0.129g, 1-second spectral response 0.064g. Among 330 Illinois cities in this dataset, Carol Stream ranks 123 for seismic hazard, the 63th percentile within the state. About 39,556 people live in Carol Stream, Illinois.

What a retrofit costs in Carol Stream

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.

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 Carol Stream address.

More on how this number was built

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