When building in tornado-prone areas, utilizing tornado proof house materials that can withstand the potential damage is critical.
The majority of tornadoes fall in the F0 to F2 range, with minimal to moderate damage at wind speeds up to 157 mph. This can include torn-off roof shingles, window damage and fallen trees.
However, F3 to F5 tornadoes with winds ranging from 158 to 318 mph can cause exterior walls to fly off, roofs to overturn and buildings to become completely decimated.
For builders located in tornado zones, choosing the right construction method, like ICF, can help mitigate damage and protect against these extreme wind forces.
Typically, homes made from ICF blocks can withstand wind speeds of up to 400km/h (250 mph) or more, which is much higher than traditional wood-frame houses. With their durability, ICF blocks could be the difference in whether a home survives a tornado or not.
ICF Construction: Advantages of ICF for Extreme Weather
ICF has immediate and long-term benefits for homes in extreme weather zones. In the event of a tornado, ICF construction with reinforced walls provides superior durability, helping homes withstand high winds and stay standing.
Beyond immediate protection, ICF blocks offer lasting advantages in terms of energy efficiency and insulation.
Their superior insulation properties help maintain stable indoor temperatures, even during power outages. This ensures comfort for homeowners when the outside elements are at their harshest. Even during calm weather, ICF helps homeowners save on year-round energy costs.
ICFs are effective at moisture control, reducing the risk of water damage from tornadoes, rain storms, humidity and snow. This combination of durability, energy efficiency and moisture resistance makes ICF homes a smart choice for long-term resilience and comfort.
Durability and Resistance
Due to their robust construction, ICFs maintain structural integrity and withstand tornado-force winds. They have a reinforced concrete core with a significant load-bearing capacity, particularly when compared to steel or wood-framed walls.
ICF blocks have five to 10 times greater racking strength — the ability to withstand lateral force – than wood-framed walls. They can also resist vertical force, meaning that a home built from them can better withstand the lateral and vertical winds that can form in a tornado funnel.
Most ICF block homes can withstand up to 250 mile-per-hour winds. Compared to more traditional construction materials, ICF blocks have up to 80% higher resistance against lateral forces.
Walls made from ICF blocks have a high bending strength, which is the maximum amount of stress they can withstand before bending or breaking. Because of this, they are four to five times more rigid than wood-framed walls.
In extreme weather situations, ICF homes typically sustain less property damage and take less time to repair. Unlike wood-framed homes, which can experience significant structural damage and require extensive rebuilding, ICF homes are more likely to remain intact, with only minimal cosmetic repairs needed.
This makes ICFs a more resilient and cost-effective option in the long run, reducing homeowners’ repair time and costs.
Energy Efficiency and Insulation
The direct impact of a storm isn’t the only thing that a house needs to be able to withstand. A tornado’s aftermath can be just as dangerous as the actual storm.
Power may be out for several weeks, meaning a homeowner will be at the mercy of the elements. ICF blocks have superior energy efficiency and insulation, so they can help maintain comfortable temperatures inside the home, even in extreme weather or without power.
That’s because ICF blocks have a solid concrete core that is surrounded by two layers of foam insulation. This design resists heat transfer and keeps the temperature inside the home stable. It can help keep a house warm in the winter and cool in the summer, saving homeowners energy costs.
ICFs have a high R-value, meaning installations don’t require continuous insulation. They also have 58% better R-value performance than conventional wall systems, resulting in energy savings of up to 60% per year.
Moisture Control
ICFs are naturally resistant to water, moisture, rot and mold, especially when a waterproof membrane is added. Their airtight construction limits air infiltration and lowers the risk of humidity buildup, helping to control moisture.
After a tornado, it is typically humid because tornadoes form within thunderstorms, which come from warm, moist air rising. ICF blocks will help control moisture and reduce the risk of mold growing inside the walls and home.
Designing for Tornado Resistance
Homes built in states with a long tornado season must be tornado-resistant. These states are known as “Tornado Alley” and include:
- Texas
- Oklahoma
- Kansas
- Nebraska
- South Dakota
- Iowa
- Missouri
- Illinois
- Indiana
- Ohio
Tornado proof design should be a top priority if you live in one of these states.
As tornadoes continue to impact areas across the Southeast and Midwest, architects and builders must consider home design features that will make their homes as tornado-resistant as possible.
Key Features of a Tornado Proof House With ICF
Making sure a home’s walls, roof and windows are ready to withstand tornado-force winds and possible direct hits from flying debris is a good place to start when designing a home that will last.
Reinforced Walls and Foundations
Reinforcing a home’s walls and foundation with ICFs improves its structural integrity. The unbroken surface of ICF block walls allows wind to flow over them without obstruction, reducing the risk that the walls will buckle or bend.
A foundation of ICF blocks is a slab of solid foam-reinforced concrete with no weak points that could allow winds to lift the home or move it off the foundation.
Traditional wood-frame homes have gaps or joints between the walls and foundation, where wind pressure can cause structural failure. However, using ICF blocks eliminates those gaps, making the home’s structure more secure.
Secure Roof and Window Installations
Hurricane straps and clips, otherwise known as metal connectors that attach a building’s roof to its walls, can help secure the roof of a home during a tornado. However, replacing the roof with one made from wind-resistant materials that are properly sheathed is the best option for high wind defense.
Metal roofing is the most resistant to high winds, with overlapping panels providing superior strength. Other options are concrete, clay or slate roofing. When it comes to design, a hip roof design with multiple slopes is better at handling wind than a gable roof.
Impact-resistant windows (sometimes called hurricane-resistant windows) are specifically designed to withstand the impact of flying debris and high winds, making them the best choice for areas concerned about tornado protection.
If impact-resistant windows are out of the budget, you can protect regular windows by installing hurricane shutters to safeguard the glass from debris and high winds.
Structural Enhancements
Structural enhancements can also help protect a home from severe tornadoes. The protection upgrades in the home’s design and construction work together to create a home that can maintain structural integrity even if part of the home is damaged.
Structural enhancements can include:
- Adding Reinforcement Bars: Adding rebars to the foundation and walls of a home can increase their strength and durability. ICF blocks have rebar integrated into the blocks for extra strength, but the rebar is added during installation.
- Safe Room or Tornado Shelter: A designated safe room, typically built in the basement or interior of the home, is designed to withstand the extreme forces of a tornado. These rooms are often constructed with reinforced concrete, steel and heavy-duty doors. This can keep people safe from collapsing structures and flying debris.
- Storm-Resistant Doors: Heavy-duty, impact-resistant exterior doors can help a structure withstand high winds and debris impacts. Doors made from solid wood, metal or fiberglass with wind-rated hardware are ideal.
- Wind-Resistant Garage Doors: Garage doors are often one of the first parts of a home to fail in high winds. Replacing standard garage doors with wind-rated doors can prevent the garage from collapsing.
Installation Best Practices
ICF blocks must be installed properly to preserve their strength. Fortunately, because of the interlocking knobs that turn SuperForm ICF blocks into one continuous unit, installation is typically faster and easier than other materials.
You can attend a training to learn more about installing ICF blocks, but there are some common installation questions that you can familiarize yourself with to learn more:
- How are ICFs installed?
-
-
- You can assemble ICFs right where the building goes up, each piece fitting with the next. They are lightweight and easy to stack, and most ICFs lock together. Slide the rebar into the gaps inside to strengthen and support the structure. Pour the concrete into the forms, making one solid piece.
-
- Can I use ICF for all types of building projects?
-
-
- Yes, ICFs are flexible, making them ideal for various buildings, such as houses, offices, commercial properties and foundations.
-
- Do I need special equipment to install ICFs?
-
-
- No! You’ll need basic construction equipment, such as scaffolds, concrete mixers and tools for cutting steel bars. It’s best to hire experienced ICF workers for the smoothest installation.
-
- How do I address plumbing and electrical?
-
- Plan for wiring and plumbing before you install your ICFs. Securely lay down all lines before pouring concrete. Choose non-metallic electrical boxes and PEX tubing for plumbing. Seal all holes tightly to keep the insulation intact. Ensure everything meets building codes and consider how you’ll handle maintenance.
Common Challenges and Solutions
In most cases, the delivery and installation of ICFs is easy and without problems, but sometimes challenges arise, including:
- Handling and Placement Issues: Most handling and placement issues can be solved by using a laser level, framing square or plumb line during installation and ensuring that the forms have proper support. Periodically check each course as you stack the blocks to maintain straightness.
- Weather Conditions During Construction: If the temperature is below 5 degrees Celsius or 41 degrees Fahrenheit, you’ll need to order your concrete heated. Depending on the situation, you may also need to cover the top of your wall with heated blankets or curing aids to prevent the surface from freezing.
- Cutting Blocks to Fit: While ICF blocks interlock easily, cutting blocks to fit windows, doors or corners can be tricky. Cutting through the foam and reinforced concrete can cause messes and misalignments if not done carefully. Use the proper cutting tools, such as a handsaw or a circular saw with a foam-cutting blade. Measure carefully before cutting and follow all safety precautions when cutting blocks.
- Inexperienced Labor: ICF construction is different from traditional wood framing and requires special expertise. Workers unfamiliar with ICF systems might struggle with the installation process or make mistakes that affect the structural integrity of the walls. To ensure this isn’t a problem, work with a manufacturer who offers detailed training or hire an experienced ICF contractor.
Maintenance and Upkeep
ICFs are very low-maintenance, but it’s best practice to do some maintenance and ensure that the ICF blocks are all in good condition, especially after a tornado or severe weather event.
Regular inspections are a great way to ensure there are no cracks, chips, gaps or damage to the ICF blocks. Typically, regular inspections include:
- Checking for Structural Integrity: After a major weather event like a tornado, check the structural integrity of the ICF blocks — especially in parts of the home that were directly hit — to ensure they are still strong, level and solidly in place.
- Maintaining Seals and Weatherproofing: Seals and weatherproofing should also be checked regularly to ensure they haven’t started to fail. Failed seals could allow water to get into the walls or the foundation.
Preparing for Future Storms
Similar to regular maintenance, proper preparation can help ensure your ICF blocks maintain their integrity.
To prepare for future storms, consider:
- Updating Safety Features: Homes in storm-prone areas require regular safety feature upgrades to remain as storm-resistant as possible. Tell your homeowners to invest in impact-resistant windows and doors, add a tornado shelter if possible, stay safe with a backup generator, trim their landscaping, lock up their outdoor decor, reinforce their roof and invest in more structurally sound building materials.
- Community and Emergency Preparedness: It’s also a good idea to familiarize yourself with any community emergency preparation programs and resources for homeowners in the event of a tornado that causes widespread damage.
Discover the Benefits of ICF Blocks for Weather Resistance
Building with the right materials is essential to protecting homes and keeping them safe from the devastating impact of tornadoes. That’s where SuperForm ICF blocks shine. Unlike traditional construction methods, our ICF blocks provide unmatched strength, energy efficiency and resilience against extreme weather.
With their reinforced concrete core and durable insulation, SuperForm ICFs create walls that are not only tornado proof but also provide superior moisture control and long-term energy savings.
By choosing SuperForm ICF blocks, you’re investing in a material that can withstand the harshest conditions, from tornado-force winds to other intense storms.
Browse our wide range of ICF products and consult with our experienced design team to discover how our blocks can help you build a home that offers lasting protection, comfort and peace of mind.