Designing for Disaster in an Increasingly Dangerous World
13 mins read

Designing for Disaster in an Increasingly Dangerous World

Developers often make it sound as though their latest LEED platinum office building will single-handedly reverse climate change. The unfortunate reality is that they could spend a lifetime designing and building all of their work to meet the highest environmental standards, but it wouldn’t fix the problem. The planet will grow hotter, the seas will rise, and storms will intensify. A century of burning fossil fuels has baked global warming into the atmosphere for our lifetime. 

While we cannot stop climate change, we can mitigate it. And homes and buildings, moreover, can be constructed to resist all but the most severe weather. We regularly trotted out these best practices in Builder magazine (which I edited for 17 years) each time a tornado decimated a midwestern town, hurricanes laid wasted to the Florida coast, or Hollywood cliff-top celebrity mansions slid into a ravine. Unfortunately, designing and building homes to resist climate change is a harder challenge. 

Catastrophes create a perception that protecting against natural disasters is futile. The media deluges us with catastrophic images, but the horrific scenes belie the reality that most damage from extreme weather occurs around a storm’s periphery or from lesser storms, much of it preventable. The structural basics—strapping roofs to walls, anchoring walls to foundations, upgrading to impact-resistant glass and beefed-up garage doors, and building with fire-resistant materials—can make a huge difference. 

These moves don’t add a big expense. Builders in Moore, Oklahoma, one of the few jurisdictions in Tornado Alley with a tornado code (twisters have repeatedly pummeled the Oklahoma City suburb, killing dozens of people and injuring many times more than that) estimate that it costs about $3,000 to $4000 to meet the provisions. That’s about the same as a quartz countertop, a media wall, or a home theater—“nice to have” features that it might make sense to defer in favor of “must-haves.” 

 

Most cities subject to severe weather fail to provide a first line of defense in their building codes. FEMA recently estimated that only 32% of natural disaster–prone areas have adopted the latest, or even second-latest, model code provisions that protect against high winds, fire, flooding, and shifting earth. Cities and counties, the report notes, seem to be reacting faster to the threats of damaging winds and flooding—because these conditions affect more people and are easier to counteract—than the big menaces of hurricanes, tornadoes, and seismic shifts.

Not all extreme weather, of course, can be linked to global warming. It’s easy to connect warmer temperatures with record heat and forest fires. As air warms, it boosts evaporation, worsens droughts, and kills vegetation. Adding heavy rains after a drought creates the conditions for mudslides. A warming planet melts polar ice caps that cause seas to rise. Heavier rains result from having more moisture in the lower atmosphere. But it’s hard to find a nexus between hotter world temperatures and hurricanes and tornadoes, which are much more complicated meteorological events. 

Even so, evidence suggests hurricanes and tornadoes are growing more intense as the planet warms. Severe weather has worsened in the five years since the publication of my book Designing for Disaster. The National Oceanic and Atmospheric Administration cataloged 186 severe storms that caused at least $1 billion in damage from 1980 through 2023. Over a third of these events—with wind gusts of 58 mph or more, hail 1 inch or larger in diameter, or tornadic activity—occurred during the past five years. 

The lack of code protection leaves it to homeowners to determine threats to their houses. Government-maintained maps may not be the most trustworthy source, especially for flooding. First Street, a nonprofit that has partnered with government agencies and real estate organizations, estimates that 14.6 million properties are at risk from a 100-year flood, not the 8.7 million shown on FEMA flood maps. FEMA doesn’t adequately account for sea-level rise, rainfall, and flooding along smaller creeks not mapped by the federal government. 

Mexico Beach, Florida, ground zero for Hurricane Michael, a category 5 hurricane carrying 160-mile-per-hour winds, adopted stronger building codes in the storm’s wake. Officials decided to exceed Florida’s state code. Architects must design new homes to withstand 140 miles-per-hour winds rather than the 130 outlined in the Florida code. Builders must elevate homes 1.5 feet above the 100-year or 500-year floodplain. 

Building oceanside homes to resist hurricanes can be much more expensive than protecting a home in the plains from high winds. The big expense is raising a home above a potential storm surge, work that usually requires a concrete or steel foundation. Outlets, switches, sockets, and circuit breakers must be raised above flood levels. One disaster relief specialist, working in the wake of Hurricane Sandy, estimates that these measures add 7% to 9% to the cost of a new home—$70,000 to $90,000 in the case of a $1 million residence.

The latest best practice, referenced in model codes, is to design breakaway walls within rooms below the floodplain. That way, they don’t help bring down the rest of the house. Architect Dan Nelson employed this technique with the Tsunami House, located on Camano Island, Washington, where a tsunami struck several centuries before. Aluminum and glass walls on the first floor, purposely set in weak frames, will break away in waves, allowing water to course through the house and exit on the other side.

 

The worst damage from hurricanes often occurs after the storm hits. Retained rainfall in swollen rivers and lakes causes rampant flooding. In North Carolina, the aftershocks of hurricanes Florence, Matthew, and Michael have inundated entire communities, causing billions of dollars in damages. The state has responded by publishing better flood maps, dispensing information about how to protect homes from rising waters, and even paying to move or elevate at-risk homes.

Another common precaution: installing foundation vents that allow flood water to flow through a home rather than pool around, relieving pressure on walls and basement windows. FEMA recommends installing inexpensive backflow valves in homes that might be subject to flooding; it prefers gate valves over flap valves since they provide a better seal against flood pressure. 

Storm drains couldn’t handle the flood in Houston and surrounding Harris County, which were hit with three 500-year storms in three years. In response, the city has abandoned 100-year-floodplain guideposts in favor of the 500-year plain as a standard for regulatory purposes, building flood retention ponds, and upgrading the dam on Lake Houston. But that may not be enough, according to the Baker Institute, which stresses the need to acknowledge the real risk of flooding, install markers and signs, develop a flood-warning system, and perhaps even buy back homes in flood-prone areas. 

Hurricanes and tornadoes aren’t the only threat to Houston. According to a NOAA report, major coastal cities can expect sea levels to rise by up to a foot within the next 25 years. By 2050, moderate flooding, which is already a major problem in cities such as Annapolis, Maryland, can be expected to occur 10 times more frequently. Rising seas pose an even greater threat to cities such as New Orleans, San Francisco, and Norfolk, Virginia, that are sinking anyway. San Francisco decreed that all new construction projects show a plan for mitigating the impact of rising seawater. New York City plans to spend $20 billion to shore up its defenses. Miami Beach is raising its streets by 2 feet. 

A recent University of Vermont study concluded that while Americans are migrating away from coastal cities subject to heat waves and hurricanes, they are moving to forested areas threatened by wildfire. Once again, the number of properties at risk from forest fires may be greater than federal fire maps would have you believe. First Street recently identified 80 million properties at risk of wildfire. It considered local information about the age of properties and how they were built. The group forecasts that the number of buildings annually lost to fire will double from 17,000 within 30 years “due to climate change alone.”

A patchwork quilt of wildfire codes covers the nation. Only California, Nevada, Utah, and Pennsylvania have statewide wildfire codes, though an additional eight states publish wildfire-mitigation guidelines. Colorado last year set a path to enact a statewide wildfire-resistant building code by July 2025. Washington, on the other hand, scrapped new wildfire protection rules for buildings on the day they were supposed to take effect. The state’s builders argued that new code protections would add to the cost of a home and were better left to local governments. 

One study suggests that building a prototypical home to the Wildland Urban Interface Code (WUI) can cost less. But there’s a big hitch: the analysis assumes a switch from cedar to fiber cement siding, which to some people may defeat the purpose of having a home in the woods. The material change, however, will pay for a better roof, stronger windows and doors, and fire-retardant landscaping close to the house. (The study excludes the cost of fire-resistant landscaping throughout the yard, which can be a considerable added cost.)

Wildfire codes focus on designing a fire-resistant exterior. The idea is to cover every nook and cranny because fire seeks out the weakest link: a flimsy attic vent, an unprotected eave, or a weak window. Small defenses can make a difference. Consider the case of this home in the mountains outside Sonoma overlooking the wine country directly in the path of the Norrobom Fire, part of a system of 21 Northern California wildfires in 2017. Yet this home, built with plaster-covered straw bales, survived largely unscathed. 

 

Architects Anni Tilt and David Arkin designed the house to meet the WUI, which calls for establishing a defensible perimeter. Concrete porches and decks provide a first line of defense against the fire spread. Fire encounters plaster when it meets the house at ground level. Inch-thick redwood and cedar on exterior walls naturally resists fire. Lava outcroppings around the yard—the house rests in a bowl of sorts—probably also kept fire away. In any event, the house sustained minimal fire damage, most caused by leaves trapped in grates required by the county. 

The problem is that fires keep showing up in unexpected places, like suburbs miles from forests, as was the case with the Norrobom Fire, which leapt into Santa Rosa subdivisions. Yet the code provisions appear to be making a difference. One analysis of damage from the 2018 Paradise, California, fire found that slightly more than half of the 350 single-family homes built to the new fire code escaped damage. But of the 12,100 homes built before then, only 18% were undamaged.

Building homes to prevent mudslides and other types of erosion may be the priciest proposition of all; homes may require metal or concrete pillars driven deep into the ground. We got a reminder of the danger of moving earth earlier in the year when Los Angeles saw 562 mudslides and 15 red-tagged homes. The most vulnerable areas are hillsides charred by wildfires. In 2018, a debris flow in Montecito, near Santa Barbara, destroyed or damaged hundreds of homes and killed 23 people.

The slide spared the house on the cover of my book from damage, even though it’s on a cliff overlooking the Pacific. The home was built on metal piers, driven 10 to 30 feet into stable bedrock, an expensive but necessary provision. The architect set back the home 12 feet from the cliff to provide 100 years of erosion protection. A retaining wall in the backyard runs around the porch, protecting the house from runoff. 

 

The situation has clearly worsened since my book’s publication. Even as severe weather grows more common and storm damage grows, few communities have adopted tougher code protection. It remains incumbent on homeowners to figure out whether their home would be in jeopardy and work with professionals on how best to protect it. The good news—if any news regarding this subject is good—is that methods for protecting homes from natural disasters have not changed much in five years. In fact, professionals are growing more familiar with these now-vital techniques, which should eventually lower their cost.

Featured image: Rosenberg-Zuckerman house via Arkin Tilt Architects.