Standard flood due diligence in commercial real estate transactions typically begins and ends with FEMA flood maps, documents often decades out of date that focus primarily on riverine and coastal flooding scenarios. According to Albert Slap, founder of RiskFootprint™, this approach creates significant gaps in understanding actual property risks because FEMA maps exclude heavy rainfall flooding, which affects properties regardless of their designated flood zones. "FEMA flood maps don't include heavy rainfall flooding," Slap says. "They're mostly dealing with riverine-type flood risk."
The distinction between mapped flood zones and actual flood vulnerability became starkly apparent during Hurricane Harvey in 2017, which flooded approximately 150,000 Houston-area homes, 70% located in FEMA's X Zone designated as lower risk for flooding. This extreme rainfall event overwhelmed drainage systems and caused widespread flooding in areas where most property owners did not carry National Flood Insurance Program coverage, resulting in massive uninsured economic losses estimated at $125 billion. The event disproportionately affected households and businesses that believed they were in low-risk areas based on FEMA designations.
Real property buyers and lenders face similar challenges at scale, with credit officers often reviewing loans using FEMA maps that predate recent storm events, exclude rainfall-driven inundation entirely, and lack updated NOAA storm surge modeling. To address these gaps, RiskFootprint™ integrates flood models and maps from Fathom/Swiss Re, used by global insurers and reinsurers, which add pluvial or rainfall-driven flood modeling alongside riverine and coastal surge scenarios. This integration provides lenders and buyers with a more complete picture of property-level flood exposures before transactions close.
Beyond exposure assessment, determining actual building vulnerability requires understanding first-floor elevation relative to predicted flood levels. RiskFootprint™ now includes estimated first-floor elevation data from True Flood Risk's AI tool, which uses Google Street View and other imagery alongside machine learning to provide elevation data for more than 300 million U.S. buildings. This allows the platform to distinguish between properties that sit safely above flood lines versus those vulnerable to inundation.
While FEMA maps serve important functions in NFIP insurance and local building codes, consultants relying solely on these maps work with incomplete flood risk pictures. To protect stakeholders from future errors and omissions claims and ensure comprehensive due diligence, Slap advocates for full-spectrum flood assessments accounting for all water pathways to buildings, not just scenarios mapped decades ago. RiskFootprint™ reports are available for a few hundred dollars per property, making comprehensive flood due diligence accessible across residential and commercial transactions.
