The devastating flash floods in Central Texas in July were the latest in a string of tragic flooding incidents involving rivers and streams. As with the mountain river floods in North Carolina after Hurricane Helene, many people are wondering how to prevent such disasters in the future.

Could enhanced building codes help save lives and property in flood-prone areas? Perhaps. But it is important to note there are already enhanced building codes required in flood zones.

The International Residential Code (IRC) Section R306 and International Building Codes (IBC) Section 1612 spell out construction requirements for structures built in flood hazard areas. These provisions equal or exceed the minimum construction standards established under the National Flood Insurance Program (NFIP) required for communities to be eligible for federal flood insurance for buildings constructed in flood hazard areas.

The NFIP minimum construction standards and the I-Codes require new construction and existing buildings that have been substantially damaged by a flood or other event or substantially improved in a remodeling project to be elevated above the depth associated with a flood with a 1% chance of occurring in a year (100-year flood). Construction in floodways — the areas adjacent to a river or other flood source prone to the deepest, fastest-moving floodwaters that cause the most damage — is heavily restricted.

But the nature of flooding makes the uniform development and application of standards, codes, and building requirements very difficult. Floodplains come in many shapes and sizes, including deep river valleys, broad floodplains adjacent to lakes, and coastal areas subject to ocean waves and storm surge.

For example, the Hill Country along the Guadeloupe River, the Asheville region in North Carolina, and the Appalachian areas of eastern Kentucky where severe floods recently occurred are all characterized by mountain valleys and river channels conducive to fast-moving waters and flash flooding. This is in contrast to the areas of the Great Plains along the Missouri and Mississippi rivers where floodplains are often broad and floodwaters can be shallower and slower moving.

In the built environment, shallow urban flooding can occur when storm drains get overloaded.

This variability is baked into flood zone management. Flood Insurance Rate Maps (FIRMs) developed by FEMA identify specific flood hazard areas around water based on the probability of flooding. These include the traditional 1% annual chance (100-year) floodplains, known as special flood hazard areas, floodways, and on some maps the 0.2% annual chance (500-year) floodplain. These mapped flood hazard areas are crucial in determining the risk basis for flood insurance rates and the issuance of building permits.

Even predictive modeling can fail to account for anomalous climate events. A meteorologist reported that 1.5 times more moisture was transported to western North Carolina last year than in any prior recorded event, and the North Carolina State Climate Office said rainfall amounts were well past 1,000-year flood levels.

Additional building codes will never be able to account for these types of events. But buildings built to current codes do withstand flooding far better than older structures. Home owners also have the option to build their homes to above-code standards, including for flood prevention, for an additional cost.

An upcoming cost study from Home Innovation Research Labs estimates the cost of 1 foot of elevation above grade for a typical slab-on-grade home as ranging from $4,800 to $12,200 depending on the method used and climate zone. The incremental cost of an additional foot of elevation ranges from $3,700 to $14,000. Those are significant costs for home owners and renters, especially as America is facing a serious housing affordability crisis.

In addition, Home Innovation Research Labs and NAHB recently developed a series of guidelines published by HUD for designing homes for natural hazards, one of which is for water risks. Also, the National Green Building Standard (NGBS) is currently set to be published in the next few months with an updated standard. The standard includes topics such as resiliency from water events.

A number of home building strategies and techniques can be used to prevent flooding, although hazards persist. Unfortunately, flooding is an intractable issue, but home builders and remodelers are mitigating these risks and hazards with new techniques and products based on science.