Oak Lawn's Seismic Design Category, explained

USGS's ASCE 7-16 seismic design model - the same standard building codes use - places Oak Lawn in Seismic Design Category B: Low seismic hazard. Code requires basic seismic detailing (bracing, connections) but no special structural system restrictions. Rank it against the rest of the country and Oak Lawn sits at the 40th percentile for seismic hazard among 4,875 US cities.

Oak Lawn by the numbers

The raw figures: peak ground acceleration 0.063g, short-period spectral response 0.125g, 1-second spectral response 0.066g. Among 330 Illinois cities in this dataset, Oak Lawn ranks 171 for seismic hazard, the 48th percentile within the state. About 56,531 people live in Oak Lawn, Illinois.

Bracing and bolting: the actual cost

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.

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 Oak Lawn address.

More on how this number was built

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