Lemont's Seismic Design Category, explained

Under the seismic model IBC and ASCE 7 use for new construction, Lemont is 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 Lemont sits at the 43th percentile for seismic hazard among 4,875 US cities.

Where Lemont sits in Illinois

USGS's underlying values for Lemont: 0.068g peak ground acceleration, 0.133g at short period, 0.067g at 1 second. Within Illinois alone, Lemont ranks 112 of 330 cities by seismic hazard - the 66th percentile in-state. Lemont has a population of about 18,203.

Bracing and bolting: the actual cost

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 Illinois 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 Illinois.

What this means for insurance

A Lemont 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 Lemont's figures come from

Lemont's Category B 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 B does and doesn't tell you about Lemont.