More than 40% of all U.S. homes are at high or very high risk for natural hazards, according to a report released by RealtyTrac. The firm's 2015 US Natural Disaster Housing Risk Report found that 35.8 million U.S. single family homes and condos with an estimated value of $6.6 trillion are in counties with high or very high natural hazard risks. Those homes represent 43% of the 83.4 million single family homes and condos in all counties analyzed for the report.