The new code requires homes and business located within the 100-year floodplain to be built two feet above the 500-year floodplain to mitigate flooding to structures, Harris County Judge Ed Emmett said.
According to the Harris County Flood Control District, the 500-year floodplain is the area of land that has a .2 percent chance of flooding each year. A 100-year floodplain is the area that has a 1 percent chance of flooding each year.
The new code does not affect Harris County lands located within municipalities, such as the cities of Houston, Tomball or Jersey Village.
The regulation, which affects all new construction permits, is likely to have spared many homes from flooding during Hurricane Harvey, Emmett said. The new code was unanimously approved by Harris County commissioners during a Dec. 5 meeting. Hurricane Harvey hit the Greater Houston area in late August, dropping as much as 52 inches of rain over five days.
“After the regulation we adopted today, Harris County will have the stiffest building code regulations in the country,” Emmett said. “And part of that is, you can talk about 100-year floodplains [and] 500-year floodplains, [but] nobody really cares about that. People care about how high is the water going to get. So if those [floodplain] maps are wrong we need to err on the side of caution going forward.”
Editing the building code is a preliminary measure as the county waits for the Federal Emergency Management Agency to change the federal maps that determine the 100-year and 500-year floodplains, Emmett said.
Detention and flood mitigation requirements are based on the FEMA floodplains. However, it took seven years for FEMA to edit the floodplain maps after Tropical Storm Allison in 2001, leaving the county seeking more immediate solutions, Emmett said.
“The maps are going to change, but we can’t wait for FEMA to redo all of the maps,” Emmett said. “We can use what we have. That’s why we’re erring on the side of caution. We’re getting people well above what we think the water is going to be at in the future.”
Despite increased costs, developers and builders have responded positively to the new regulation, he said.
“Going forward we want to make sure that no one is building in an area that is going to flood,” he said. “Nobody wants to build a home that’s going to flood, particularly after what we’ve been through over the last two years.”