Property insurers face an estimated $18 billion bill for damage to homes and businesses from the long stretch of frigid weather in Texas and numerous other states, the equivalent of a major hurricane, according to a leading risk-modeling firm. Over half of the payments will be headed to Texas, and businesses—rather than homeowners—will receive the majority of the payouts, according to Boston-based Karen Clark & Co., which runs catastrophe-modeling software widely used in the U.S. insurance industry.

Much of the damage stems from widespread freezing of pipes, which have burst inside schools, museums, churches, commercial spaces as well as homes, leading to extensive water damage, Ms. Clark said in an interview Friday. The damage is spread over about 20 states. Besides Texas, hard-hit states include Arkansas, Missouri, Oklahoma and Tennessee, Ms. Clark said.

“This event has snow and ice, but it is predominantly a freezing event and most of the claims  are going to be related to water damage,” she said. Her firm’s estimate incorporates collapses of commercial roofs, “and a sprinkling of lots of different types of claims, but they will be dominated by water claims.”

She called it “a perfect storm” in the way it paired extremely low temperatures with snow and ice that contributed to power outages, and the extreme temperature anomalies lasted longer than this type of weather usually does in southern states.

If the industry’s tab does turn out to be $18 billion, the winter storm will end up on the top-10 list of costliest natural catastrophes in the U.S., as measured by losses to property insurers.  It would fall just below Hurricane Ike in 2008, which cost the industry $21.51 billion, according to trade group Insurance Information Institute.

Ike is in eighth place on the trade group’s list. In ninth place currently is a 2012 drought that caused $16.42 billion in insured damage, and Hurricane Wilma in 2005 is in 10th place, at $13.84 billion in insured damage.

“Texas was ground zero of the temperature anomalies,” Ms. Clark said. “And it wasn’t just part of Texas but the complete state.You have a lot of population being impacted.”