County tightens flood plain rules
More rigorous standards for new development could impact growth
Harris County Commissioners Court unanimously approved new, tougher regulations for floodplain development Tuesday, including a requirement that some new homes use pier and beam construction and that they be built to withstand high winds.
Spurred by Hurricane Harvey’s widespread devastation, the new rules also include higher elevations — up to 8 feet higher than previously required in some areas — and require new construction to be built to the 500-year storm standard rather than a 100year standard, opening up much larger areas of the county to regulation.
The new rules come more than three months after Harvey covered much of the county in recordbreaking rainfall, in some areas up to 51 inches over the course of the storm. The county analyzed how and where the more than 30,600 homes flooded in its unincorporated jurisdiction during the storm to design the regulations, which are slated to take effect on Jan. 1.
“That could have protected the vast majority of homes that flooded,” Harris County Judge Ed Emmett said.
Matthew Festa, a professor of land use law at South Texas College of Law Houston, said the regulations could impact growth in unincorporated Harris County, where the lion’s share of Houston’s expansion has occurred in recent years. Unincorporated Harris County has added nearly 1 million people since 2000.
“The regulations make
it more expensive, so one impact could be less development,” Festa said. “But there’s still going to be demand. This could make it less efficient for developers to keep doing what they’ve been doing. At a bare minimum, it’s going to be more expensive to build each house.”
He said the new rules also could impact the feel of neighborhoods built decades ago to older standards — some homes, damaged during storms, will have to be elevated while others remain at a lower level, creating a patchwork feel. Festa said regulations could be a disincentive to build in wider areas of the county, which could encourage sprawl.
“The developer’s next move might be to say, ‘OK, we’re not going to build in the 500-year floodplain,’” he said.
The Greater Houston Builders Association, Houston Real Estate Council, American Council of Engineering Companies of Houston, Houston Apartment Association and the Houston chapter of the American Institute of Architects had written letters to the county supporting the regulations.
Ed Taravella, chairman of the Community Developers Council for GHBA, said builders of large subdivisions generally avoid floodplains, so they would not be affected by the new regulations.
‘Hard to quantify’ effect
According to county figures, since 2009, when a set of county infrastructure regulations were put into place to address drainage issues, more than 75,000 homes have been built in unincorporated Harris County.
Of those, 467 flooded during Harvey, which Taravella said indicated that even current regulations largely were effective during the storm.
He said those that will be affected by the new regulations could include those seeking to rebuild homes in older neighborhoods damaged by floods. He said the cost to meet the new regulations likely would be in the thousands and would depend on such factors as topography and how deep in a floodplain the home is.
“It could be pretty wide ranging,” he said. “It is really hard to quantify.”
So-called 100-year floodplains are based on a storm so severe that it has a 1 percent chance of occurring in any given year and equates to between 12 and 14 inches of rainfall in a 24-hour period across the county. A 500-year event has a 0.2 percent chance of occurring in any year and equates to between 17 and 20 inches of rainfall in 24 hours.
The floodplains and flood levels are mapped by modeling how water spills out of the creeks, bayous and ditches during those storms and how high the water would rise. For the more severe 500-year storm, water spills out in much wider areas.
For some areas along the San Jacinto River, Spring Creek and Cypress Creek, the difference between the new and old regulations — 500-year versus 100-year flood levels — could be several feet of elevation required for new homes, which could increase the cost of development by thousands of dollars.
For the wind protections, the regulations state that homes should be able to “withstand a three-second gust basic wind speed of 120 miles per hour.”
Those protections could include reinforcing straps that connect rafters and walls, County Engineer John Blount said.
Homes in the 100-year floodplain need to be raised on pierand-beam or other foundations that allow water to flow through, according to the regulations. That could increase the cost of building a home rather than simply using a concrete slab foundation that sits directly on the ground.
Watching for ‘undue burden’
Precinct 1 Commissioner Rodney Ellis said he thought the new regulations “move us in the right direction.”
“We are experiencing a new normal, and it’s clear we need to be planning for the future and building resilient systems that can withstand extreme weather, from flooding to drought,” Ellis said in a statement. “Since Harvey’s floodwaters receded, we’ve been confronted with complex, intersecting issues surrounding new and existing developments, infrastructure, housing and climate change.”
Precinct 4 Commissioner Jack Cagle, while casting a vote in favor of the new regulations, said he wants to monitor the impact of the regulations to see if they create an “undue burden” on developers or those seeking to buy new homes. He said the benefits would have to be weighed against the cost of potentially losing the county’s affordability.
“This is a work in progress,” Cagle said.
The floodplain regulation changes were one component of Emmett’s 15-point plan to revamp flood control that he proposed in October. He said they were necessary to protect future homes from a Harvey-level deluge.
“Nobody wants to build a house that’s going to flood,” he said.