Flood Exposure, Assessed Losses, and Resale Prices:\ Evidence from Florida
This study of Florida's housing market reveals that while significant flood damage often goes unrecorded by appraisers, homes with substantial water exposure still suffer persistent resale price discounts driven by physical damage rather than appraisal flags, and the absence of a flagged write-down does not guarantee a property remained dry.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
When a house is damaged by a flood, its value often drops. This is a basic economic truth: a home that has taken on water is worth less than an identical home that stayed dry. But measuring exactly how much less is surprisingly difficult, especially when the damage record itself might be influenced by the sale price. In the real estate world, property appraisers determine a home's value for tax purposes. If a house sells for a low price after a flood, an appraiser might lower the official tax value of that home. This creates a tricky loop: did the flood cause the low price, or did the low price cause the appraiser to write down the value? For lenders, insurers, and disaster relief agencies, knowing the difference is critical. They need to know if a low price reflects the physical reality of water damage or simply the paperwork that followed a sale.
A new study from Florida tackles this question by looking at thousands of homes that were sold before and after six major hurricanes between 2017 and 2024. The researchers wanted to see if the official tax records accurately captured the water damage, or if they missed a lot of it. They also wanted to find out how much money a flooded home actually loses in value, independent of what the tax appraiser wrote down. To do this, they ignored the tax appraisers' notes for their main measurements. Instead, they used independent data sources: computer models that estimated how deep the water was at each specific house, reports from field inspectors who walked through neighborhoods after the storms, and records of building permits for repairs. By comparing these independent facts with the actual sale prices of the homes, the team could see what the market was really saying about flood damage.
The study began by checking how well the official tax records matched the independent data. The researchers found that the tax appraiser's "flag"—a signal that a home's value had been significantly reduced—was an imperfect guide. While the flag did appear more often on homes with deeper water or severe damage, it missed the vast majority of flooded houses. Specifically, nearly 79 percent of homes that had at least one foot of water inside them did not carry a flag on their tax record. Conversely, some homes that were flagged had no recorded water at all. This suggests that relying solely on tax write-downs to identify flood damage would leave out most of the affected properties. Furthermore, the study found that these flags were not more common on homes that sold quickly after the storm, which means the appraisers were not simply reacting to a low sale price to create the flag.
When the researchers looked at the actual resale prices, a clear pattern emerged. Homes that had at least one foot of water sold for significantly less than similar homes in the same neighborhood that had not been flooded. On average, these inundated homes sold for about 5.3 percent less than their dry neighbors. This discount was not just a temporary shock; it persisted even in sales that happened two or more years after the storm. In fact, for every additional foot of water depth, the price dropped by another 0.6 percent. This relationship held true even when the researchers compared homes within the same flooded neighborhood, ensuring that the price drop was due to the water at that specific house and not just general neighborhood decline.
The study also examined the timing of the sales to understand why flagged homes sometimes sold for even lower prices. The data showed that the extra discount on flagged homes was concentrated in sales that happened very soon after the hurricane. These early sales often involved homes that had little or no recorded water, yet still sold for much less than their peers. This suggests that the large price drop on flagged homes was not caused by the flood itself, but by other factors, such as wind damage that was repaired before the sale, or perhaps the stigma of the sale itself. Once the market settled and sales occurred two years or later, the price difference between flagged and unflagged homes became statistically indeterminate; the data could not confirm whether a difference remained or not, indicating that the early discount was not the price effect of flooding.
Another key finding concerned the selection of which homes were sold. The researchers investigated whether flooded homes were more or less likely to be put back on the market. They found that homes with at least one foot of water were actually slightly more likely to be resold than homes with less water. This is an important detail because if flooded homes were harder to sell, the average price of the ones that did sell might look artificially low. Since they were selling more often, the price drop observed in the study is a genuine reflection of market value, not a statistical trick caused by only the most desperate sellers showing up.
Finally, the study looked at homes that stayed completely dry but were located in neighborhoods where many other houses were flooded. Even these dry homes saw their values drop, but only if a large portion of their immediate neighborhood had been inundated. For every 10 percent increase in the number of flooded homes in a neighborhood block, the price of a dry home dropped by about 0.5 percent. However, this effect was less certain and harder to pin down than the direct damage to the houses themselves. The researchers noted that this neighborhood effect might be influenced by factors other than the flood, such as pre-existing trends in the area, and it was not as strong or consistent as the direct price hit from water entering a home.
The implications of these findings are significant for anyone dealing with flood risk. For lenders and insurers, the study shows that a tax write-down is not a reliable way to identify a flooded home, as it misses most of them. Relying on these records could lead to underestimating the risk and the true cost of damage. For disaster aid, programs that distribute money based on official damage records might be leaving out the majority of homeowners who actually took on water. The most accurate measure of value loss comes from the physical reality of the water depth, which continues to depress prices for years after the storm. While repairs can restore a home, the market still prices in the history of the flood, particularly for homes that took on a significant amount of water. The study concludes that to understand the true cost of flooding, one must look past the paperwork and measure the water itself.
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