Abstract

Climate-related risks to housing have become increasingly significant, demanding a proactive, systems-based approach to resilient home design, renovation, and construction. This article synthesizes the research and strategies developed by the Insurance Institute for Business and Home Safety (IBHS) through its Fortified program, as presented by Alexandra Cary, Fortified Market Development Director. It explores the science and practical applications behind reducing risk, impact, and insurance costs for homes exposed to wind, hail, hurricanes, and other natural hazards. The article is written for housing professionals, builders, contractors, and the interested public, offering in-depth, actionable knowledge for building stronger, safer, and more sustainable homes.

Introduction

The intersection of climate change, the increasing frequency of catastrophic weather events, and the vulnerability of the housing stock presents a challenge—and an opportunity—to the building industry. Over the last several years, natural disasters have inflicted hundreds of billions of dollars in damage to homes and communities across the United States. The Fortified program, developed by the Insurance Institute for Business and Home Safety (IBHS), translates decades of scientific research into practical standards for improving the resilience of homes and buildings. By focusing on predictable failure points, especially in roofing systems, and by promoting third-party verification and documentation, Fortified offers a clear pathway to reducing losses, accelerating recovery, and ensuring that investments in sustainability and efficiency are matched by investments in durability and safety.

The Scope of the Challenge

Between 2020 and 2024, the United States experienced over $750 billion in damages from a range of natural disasters—wildfires, hurricanes, tornadoes, derechos, severe thunderstorms, and, notably, hail. The impact of these events extends well beyond financial loss: they displace families, disrupt communities, and strain public and private resources. Insurance companies, who shoulder much of the recovery cost, have driven research into how homes fail and what can be done to prevent such failures. This has led to a focus on actionable standards and practical solutions, aimed at investing modestly up front to avert far greater losses later.

The IBHS research center stands at the forefront of this science, with capabilities to simulate hurricane-force winds, create realistic hail, and conduct full-scale residential and commercial building tests. The findings from these experiments are clear: roofs are the most common and most critical point of failure. When roofs fail, the resulting damage can cascade through the entire structure, often rendering homes uninhabitable and leading to extensive, costly repairs. Despite this, roofs remain one of the least inspected and least enforced elements in building codes across much of the country.

From Research to Action: The Fortified Program

The Fortified program addresses these challenges with a systems-based, research-driven approach to home resilience. It is designed to be voluntary, scalable, and applicable to a wide range of buildings—from single-family homes to multifamily and commercial structures. Fortified is not a warranty or insurance policy, nor does it guarantee zero damage; rather, it is a method for reducing the frequency and severity of loss, accelerating recovery, and providing peace of mind for property owners.

Fortified standards are organized into three main levels:

1. Fortified Roof: The foundational level, focusing on keeping the roof intact and water out of the home. Key requirements include enhanced deck attachment, sealing the roof deck, and securing the roof edges with drip edge and starter strips.
2. Fortified Silver: Building on the roof level, Silver addresses damage amplifiers—components such as garage doors, openings, porches, and gable ends that, if compromised, can lead to catastrophic structural failure.
3. Fortified Gold: The highest level, requiring a fully continuous load path from the roof to the foundation, and design pressure verification for openings and structural sheathing to ensure the entire building envelope is resistant to extreme pressures.

Hazards Addressed and Regional Variations

Fortified standards differentiate between hurricane-prone and high-wind regions. While the program does not address flooding (which is typically managed by federal programs), it does provide optional supplements for hail resilience—a critical concern in many inland regions. Most tornadoes, for example, are in the EF0-EF2 range, and Fortified standards can significantly reduce damage and displacement even in these events. In documented tornado outbreaks, applying Fortified standards has been shown to reduce the area and severity of damage by 40–65% in affected zones.

Technical Details: Roofing, Attachments, and Materials

The Fortified approach to roofing centers on details that are often overlooked but make a profound difference in resilience.

• Deck Nailing: Using ring shank nails at 4 inches on center, rather than the wider spacings found in some codes, doubles the uplift resistance of the roof deck for a relatively small additional cost.
• Sealed Roof Deck: Applying approved tape or membranes over deck seams can keep up to 95% of water out of the attic, as demonstrated in comparative laboratory tests. This simple step can prevent the equivalent of multiple bathtubs of water from entering a home during a roof-cover loss.
• Edge Securement: Fortified standards require drip edge over the underlayment and secure nailing patterns, along with fully adhered starter strips or flashing cement, to create a continuous load path and seal out wind and water.
• Roof Coverings: For shingles, Class F or H wind ratings are required. For other materials (metal, tile, low-slope roofs), third-party testing to site-specific design pressures is essential. Hail-prone regions may opt into a supplement requiring shingles with demonstrated resistance to realistic ice-ball impact, as tested by IBHS.

Material agnosticism is a hallmark of the Fortified program; the focus is on performance and verified testing, not brand or specific product. Proper installation, as always, is critical—metal roofs, for example, may perform very well or very poorly depending on how they are attached and flashed.

Beyond the Roof: Garage Doors, Openings, and Load Paths

Failure of a garage door under wind pressure can lead to catastrophic damage, including roof deck loss and wall collapse. Fortified Silver requires pressure-rated garage doors, and in hurricane zones, impact-rated windows and doors. Porches and attached structures must be securely anchored, and gable end bracing is required to prevent wind-driven failures.

At the Gold level, continuous load path requirements ensure that the forces of wind are transferred from the roof through the walls and into the foundation, minimizing the risk of structural separation or collapse. This is especially important in hurricane-prone areas, where pressures are highest and failure can be most destructive.

Verification, Documentation, and the Role of Evaluators

A unique strength of the Fortified program is its emphasis on third-party verification. Independent evaluators document every step of the process, from material selection to installation and fastening patterns, using geotagged photographs, manufacturer documentation, and compliance forms. This rigorous approach ensures that the intent of the standard is met in the field and provides a verified record for property owners, builders, and insurers.

The designation, valid for five years, is tied to the property address and is fully transferable between owners. Renewal requires confirmation that the roof and critical systems remain in compliant condition and that no unverified modifications have been made.

Retrofit vs. New Construction

While Fortified Gold is most commonly achieved in new construction, Silver and especially Roof-level designations are accessible for existing homes, particularly during re-roofing projects. Gut rehabs or post-disaster rebuilds may achieve higher levels if documentation and access permit; however, the majority of retrofits focus on the most impactful, accessible upgrades such as roof deck enhancements and garage door replacements.

Application to Multifamily and Commercial Structures

Fortified standards extend to multifamily and commercial buildings, with adaptations for building type and function. Additional requirements may apply, such as elevated mechanicals in flood-prone areas and backup power provisions for critical commercial operations. Evaluation for these structures is typically managed by risk engineering firms rather than individual evaluators, but the principles remain the same: systems-based, performance-verified resilience.

Incentives, Grants, and Growing Adoption

A growing number of states—including Alabama, Louisiana, North Carolina, South Carolina, Oklahoma, Kentucky, and Maine—now offer grants or insurance premium discounts to encourage Fortified construction. For example, Alabama provides up to $10,000 for homeowners to re-roof to Fortified standards, and Louisiana is implementing mandatory premium discounts. Federal and regional grant programs, such as those through the Federal Home Loan Bank, are increasingly tied to resilience standards like Fortified, especially for affordable and multifamily housing.

Private insurance carriers, too, are offering endorsements or premium reductions for Fortified homes, recognizing the proven reduction in claims frequency and severity. In hurricane Sally, for instance, Fortified homes were 70% less likely to file a claim than traditionally built homes, and average claim amounts were reduced by over 20%.

Performance in the Real World

Field evidence strongly supports the efficacy of the Fortified approach. After major storms, including hurricanes and tornadoes, homes built or retrofitted to Fortified standards consistently outperform their conventional counterparts. The difference is not only in the reduction of damage but in the speed of recovery—families are able to return to, or remain in, their homes much sooner, reducing displacement and community disruption.

Integration with Sustainability and Energy Efficiency

Resilience and sustainability are not competing priorities. In fact, resilient construction is essential for ensuring that investments in energy efficiency and green building are not rendered moot by disaster-related displacement or damage. Material choices—such as the use of ice and water shield, closed or open cell foam, or specific roof coverings—must be balanced for both resilience and building science best practices, including the avoidance of trapped moisture and adherence to manufacturer and code requirements.

Professional Training and Resources

For builders and contractors, the Fortified program offers accessible online training and certification, particularly for roofers. Design professionals, evaluators, and contractors can all access technical documents, CAD-ready details, and checklists to streamline compliance and documentation. As adoption grows, more manufacturers are aligning their products and systems with Fortified requirements, making it easier to specify and install compliant assemblies.

Key Takeaways

• Roofing is the critical first line of defense against wind, hail, and water intrusion; details in fastening, sealing, and edge protection are essential.
• Fortified standards are systems-based and scalable, addressing predictable failure points from the roof to the foundation.
• Documentation and third-party verification are crucial to ensuring compliance and performance.
• Retrofit opportunities exist, especially at the roof and Silver levels, making resilience upgrades accessible for existing homes as well as new construction.
• Fortified homes experience fewer and less severe insurance claims and recover more quickly after disasters.
• Incentive programs and insurance discounts are expanding rapidly, making resilience upgrades more affordable.
• Proper installation and adherence to tested, verified assemblies are more important than any specific material choice.
• Integration of resilience with green building and energy efficiency ensures long-term sustainability and occupant safety.
• Professional training and resources are available to support implementation and verification.

Green Home Institute is committed to promoting best practices in sustainable, resilient, and healthy home construction. For technical details, training, and further information on the Fortified program, professionals are encouraged to consult the IBHS and Fortified Home resources.