"Someone is going to have to make a determination if a property is salvageable or if it needs to be replaced," she said. "And if you don't have temporary housing in place to relocate people while improvements are made, you're in an even more difficult situation. Miami-Dade doesn't have suitable temporary housing. The problem is almost too big to get your arms around it."
Murray said Miami-Dade County's hurricane vulnerability can't be compared to any other municipality in the state - even Broward or Palm Beach - because they have newer housing and fewer flooding zones.
"Economically, we would get hit harder than any other part of South Florida," he said. "We've been very lucky since Andrew."
To determine the magnitude of the issue, the Metropolitan Center used Miami-Dade Property Appraiser records and the 2018 U.S. American Community Survey performed by the U.S. Census to determine 714,444 housing units - or 70.2% of the county's total 1,016,653 single-family homes, condos, townhouses and mobile homes - were built before 1990.
The study then broke out those units into two groups: Those with an assessed value lower than 50% of the current market value (103,498 units) and those with an assessed value lower than 80% of the current market value (172,114).
"The assessed current values of these properties provide an indication, since they were built before the Andrew building code, so they would be the most vulnerable," Murray said.
Both groups are prone to considerable damage or even destruction from a Category 5 hurricane. According to U.S. Census data, these structures house an estimated 815,721 people.
Predictably, most of the vulnerable properties are clustered within Miami-Dade's poorest neighborhoods with the highest percentage of African-American and Hispanic residents. Those include Little Haiti, Overtown, Liberty City, Homestead, Opa-Locka, west Coconut Grove and North Miami.
"When you have old housing stock that is generally under-capitalized, hasn't been rehabbed and is also the most affordable, it makes sense that people who have the fewest means are living there - the blackest and brownest of our population," said Annie Lord, executive director of Miami Homes for All, a non-profit housing advocacy group.