This Habitat for Humanity home was built to the FORTIFIED Gold™ standard and withstood Category 5 Hurricane Michael.
All photos courtesy IBHS
A new severe-weather standard aims to prevent minor roof storm damage from becoming catastrophic.
By Julie Lowrey, FORTIFIED Engineering Director at the Insurance Institute for Business & Home Safety
When Hurricane Ian swept across Florida in 2022, more than 5,000 homes were destroyed, 30,000+ were damaged, and thousands of families were displaced. While the storm’s surge wreaked havoc on waterfront communities, researchers from the Insurance Institute for Business & Home Safety (IBHS) discovered that the storm highlighted the effectiveness of windstorm resilience and modern building codes.
The 2023 study of storm damage examined nearly 4,000 structures. It concluded that the modern Florida Building Code (FBC)—along with its design levels, system of adoption and enforcement, and code-official training—nearly eliminated structural damage caused by wind during Hurricane Ian for homes built under the modern FBC.
“We estimate the Florida Building Code saved between $1 and $3 billion in structural damage to single-family homes alone,” explained IBHS Managing Director for Standards and Data Analytics Dr. Ian Giammanco. “While that’s a huge number, the real takeaway is that homes can be built or re-roofed in a way that minimizes wind damage.”
A demonstration at the IBHS Research Center highlights the damage that can occur when water enters a home.
After decades of research, IBHS developed the FORTIFIED Home standard for homeowners and their contractors. The methodology provides construction and roofing guidelines to strengthen areas of a house vulnerable to severe weather. The standard is free and offers three levels of protection (Roof, Silver, and Gold).
More than 65,000 homeowners have opted to go a step further by seeking a FORTIFIED designation. To receive the certificate, documentation that a home was built or re-roofed in compliance with the standard must be submitted to IBHS by an independent, third-party evaluator. This kind of designation is often required for incentives like insurance discounts, tax credits, or mitigation grants.
“The primary goal of FORTIFIED, and really of anyone seriously interested in reducing their risk from storms, is to prevent cascading damage,” says IBHS Managing Director of FORTIFIED Fred Malik. “That’s when relatively minor damage leads to bigger problems, like when some lost shingles allow water to get inside a home and ruin ceilings, walls, floors and contents.”
IBHS research shows that 70% to 90% of all post-catastrophe claims include damage to the roof, often leading to interior damage that can displace families until repairs are complete.
A demonstration at the IBHS Research Center highlights the damage that can occur when water enters a home.
Preventing roof storm damage
To limit the impact of wind damage to a roof and reduce the risk of storm damage inside, IBHS advises the three-step approach that makes a FORTIFIED Roof:
1. Strengthen connections to keep the roof deck attached to the house
Nailing a wood roof deck to the trusses or rafters below with 8d ring-shank nails in an enhanced fastening pattern can double the uplift a roof can resist. When building new, this upgrade adds virtually no cost.
2. Reinforce edges to protect one of the roof’s most vulnerable areas
Roof edges typically face the highest wind pressures on a home during a storm. A FORTIFIED roof will include wider drip edge metal and stronger underlayment—installed with enhanced fastening and secured under the drip edge. An adhered starter strip helps keep the edges intact.
3. A sealed roof deck to prevent rain from entering the home, even if shingles are lost
IBHS testing shows that asphalt shingles, particularly as they age, can dislodge in winds as low as 60 mph. Once the roof cover is lost, rain can pour into a house through the gaps in the wood roof decking.
The FORTIFIED Home standard details four different methods to cover these gaps and reduce this risk by as much as 95%. The two most common methods are covering the gaps with a four-inch modified bitumen tape or covering the entire roof deck with a fully adhered underlayment (sometimes called an ice and water shield).
Preventing hail damage
In hail prone areas, IBHS recommends a fourth step: using effective hail–impact-resistant materials.
IBHS studies show that not all impact-resistant shingles are designed equally, with differences in manufacturing methods leading to noticeable variations in performance and durability. The nonprofit’s pioneering hail research led to its Impact-Resistant Shingle Performance Ratings. These provide information necessary for homeowners to make informed decisions and choose high-performing products that minimize hail damage to roofs.
The impact test protocol addresses a critical gap in the existing hailstorm damage test standards by replacing the steel balls typically used with realistic hailstones created daily at the IBHS Research Center. Widely released in 2019, the Hail Shingle Rating scorecard is updated every 2 years.
Shingles rated as “good” or “excellent” in the overall performance ratings qualify for use for a Hail supplement to a FORTIFIED Home designation.
To better predict real-world results, researchers at IBHS use lab-created hailstones to test the effectiveness of shingles rated as impact-resistant.
During storms, garage door failure allows wind and pressure to build inside the home, often resulting in damage to the walls and/or roof.
More steps to a stronger home
After fortifying your roof, the next step to a storm-resistant home is ensuring you have a garage door with a design pressure rating of 130 mph or higher. If a garage door fails, wind pressure builds inside the garage and pushes up on the roof and out against surrounding walls, often resulting in structural damage to the entire building.
One report studied damage caused by Hurricane Ike in 2008; the Joplin, MO, tornado of 2011; and the Moore, OK, tornado of 2013. IBHS found that less than 10% of homes with an intact garage door suffered structural damage to the roof.
While the garage door is typically the largest and most vulnerable opening, windows, doors, and skylights can also be breached, admitting storm pressure, wind, and rain. Installing impact-resistant window and door assemblies is one way to minimize this risk, and the most practical in areas where tornadoes pose the greatest threat of severe wind.
Unlike hurricanes, tornadoes and fast-moving derechos offer little if any advance warning. So homeowners don’t have time to install passive impact-protection systems, like hurricane shutters. Along the coast, however, tested and approved debris impact rated shutter systems provide an affordable option for preventing damage from wind-borne debris.
In hurricane areas, FORTIFIED Silver requires design pressure–rated garage doors and impact protection for all other openings, including garage doors with windows. In inland areas, only the wind-rated garage door is required. FORTIFIED Silver also calls for additional bracing and anchorage for gable ends, gable end overhangs, certain soffits, chimneys, and attached structures like carports and porches.
Strength by design
“When we look at wind damage following a significant storm, we see partially collapsed homes with no tree in sight, or entire roofs sitting yards away from the rest of a home,” said Malik. “But in most cases, this type of damage can be prevented by using inexpensive components like rafter ties and anchor bolts to create a load path that can withstand the wind and pressures brought by storms.”
When building new, or completing a major storm damage restoration, FORTIFIED Gold will provide maximum protection from severe weather. In addition to an upgraded roof and protected building envelope, a home at this level will have an engineered continuous load path connecting the roof and wall framing to the foundation. This includes how the roof is tied to the walls, how the upper story is tied to the lower story, and how the walls are anchored to the foundation.
Going beyond the code
Hurricane Ian underscored the effectiveness of the Florida Building Code. But the $112 billion dollars in estimated damage it did cause also serves as a stark reminder that more homes were built before the code modernized than after. Further, most of the country lags behind Florida’s strict code.
In its fifth edition of Rating the States, IBHS evaluates building code adoption, enforcement, and contractor licensing in the 18 states along the hurricane coastline. The report shows many state and local jurisdictions have failed to adopt or enforce modern building codes; or they’ve allowed their codes to lapse and become outdated. Thus thousands of communities remain vulnerable. In fact, after being scored on a 100-point scale, there was a 73-point disparity between top-rated Virginia and lowest-ranked Delaware.
“While uniformly enforced, modern building codes provide community resilience, all homeowners can take actions to provide additional protection against severe weather,” explains Giammanco. “The FORTIFIED standard provides a map homeowners can follow on their path to a stronger home.”
A demonstration at the IBHS Research Center shows the dramatic difference a continuous load path can make during severe weather.
The author:
Julie Lowrey, P.E. is the Director of Engineering for the Insurance Institute for Business & Home Safety FORTIFIED Program. She translates top-tier research into action to help prevent storm damage, strengthen homes and businesses, inform the insurance industry, and support thriving communities. Julie’s previous experience includes engineering consulting and design for Zabik Turner Engineering, and cold-formed steel truss engineering and design for Alpine TrusSteel. She is Past Chair (2019–20) for the Cold-Formed Steel Engineers Institute (CFSEI), and has authored two CFSEI Technical Notes. She is a registered Professional Engineer in the state of Florida and earned a bachelor’s degree in Mechanical Engineering from the University of Florida.
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