Why ICF Construction is Perfect for Oklahoma Homes in Tornado Alley

Why ICF Construction is Perfect for Oklahoma Homes in Tornado Alley

Fox Blocks insulated concrete forms (ICFs) offer Oklahoma a superior exterior wall system for combating tornadoes with winds that exceed 200 mph and projectile debris over 100 mph. Durable ICF houses, as reinforced concrete construction, provides more protection against extreme wind events and moving debris than wood or steel framing. In addition, ICFs provide Oklahoma homeowners with a more energy-efficient, durable, and fire-resistant method to construct their homes over traditional wood construction.

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As part of the "Tornado Alley," Oklahoma ranks 3rd in the country for the most tornadoes, averaging 68 between 1989 and 2019. The frequent and intense thunderstorms and tornadoes occur in the region because the area brings together three weather systems that converge, clash, and cause severe weather:

  • Dry, cold air from the northwest

  • Warm, dry air from the southwest

  • Warm, wet air from the southeast

Tragically, tornadoes in Oklahoma have caused $4.15 billion in damage since 1996 and 474 deaths since 1950. In 2013, a tor­na­do with winds of 210 mph hit and destroyed two ele­men­tary schools, and due to structural deficiencies — sev­en chil­dren were killed.

Oklahoma needs tornado-resistant ICF construction to protect homes, schools, hospitals, commercial buildings, etc., and their occupants from dangerous and destructive tornadoes.

Designing Tornado-Resistant ICF Homes in Oklahoma with Fox Blocks

Tornado-resistant design must protect a home's integrity and the family, and provide a continuous load path that considers the strength of the entire house, and impact resistance. In addition, ICC 500 storm shelters and FEMA P361 safe room design criteria are highly recommended for maximum safety for homes and all building occupants during any weather event emergency.

The Fox Blocks ICF wall system offers the strength of a continuous load path wall to resist severe winds and flying debris from the most powerful EF5 tornadoes.

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ICFs Create Continuous Load Paths to Protect Against Tornadoes

The continuous load path created by ICF walls provides the best defense for severe tornadoes. A continuous load path protects a home from the uplift and lateral (horizontal) loads by moving the loads from the roof, wall, and other building components to the foundation and into the ground.

Additionally, the wall, roof and floor integrity also ensure a solid continuous load path that will hold the house together during an intense and dangerous tornado.

Indestructible Tornado-Resistant ICF Wall Systems

Homes built with Fox Blocks ICF walls maintain their integrity during extreme tornado winds of over 200 mph. The concrete wall's strength lessens lateral twists and damage to non-structural elements like plumbing and electrical wire. As a result, tornado-resistant Fox Blocks ICFs can significantly help maintain a home's integrity during a dangerous tornado.

Impact Resistant Fox Blocks Wall Systems

Fox Blocks has conducted and passed the required missile testing for flying debris. A 2x4 missile is shot at a wall assembly at 100 mph (equivalent to 250 mph wind speed). The missile did not penetrate or damage the Fox Blocks reinforced concrete wall, meeting the specification of ICC 500 and FEMA P361. For impact resistance against windblown debris during a tornado, ICF construction is the best.

ICF Safe Room Construction

Along with tornado-resistant home construction, FEMA strongly recommends an approved safe room to maximize the family's safety during a tornado emergency.

Fox Blocks ICFs are an ideal method to construct safe spaces that meet and exceed FEMA's criteria for safe room design. Vital elements of a FEMA safe room include a full continuous load path and resistance to wind-borne debris, overturning, and uplift. In addition, the entire enve­lope of the safe room must meet the struc­tur­al standards of the ICC- 500.

Other Crucial Design Features of a Tornado-Resistant Home

Along with the walls, a tornado-resistant home design must consider the roof and floors of the continuous path. A tornado-resistant roof design with solid connections into the ICF concrete includes roof sheathing and framing built and sized for the potential wind forces of the area, so that it will move the loads imposed by the heavy winds to the below-supporting walls. Likewise, the floor joists must withstand loads of the entire floor system and vertical loads, ensuring the loads move to the shear walls in the stories below, or the foundation.​​

Fox Blocks Create Energy-Efficient, Durable, and Fire-Resistant Homes

Fox Blocks provides benefits to Oklahoma homes in addition to energy efficiency, durability, and fire resistance:

  • Fox Blocks, with an R-value of 23, exceeds ASHRAE/ANSI 90.1 energy code requirements. It keeps homes in Oklahoma cool during their hot and muggy summers, and warm during their cold and snowy winters.

  • Durable ICF resists moisture to stop the growth of structurally damaging mold. Fox Blocks lack organic material, which pests like termites eat. Fox Blocks recommends Polyguard Products, Inc. 650 XTM or 650 XTP membranes for termite and waterproofing protection.

  • Fire-resistant Fox Blocks have an ASTM E119 fire rating of four hours, and ASTM E84 reported values for flame speed below 25 and smoke development of less than 450. Oklahoma homes need fire resistance to battle increasing wildfires. In 2020, Oklahoma had 1,241 wildfires, burning 102,302 acres of land, the 14th overall in the country.

Fox Blocks ICF Protect Oklahoma Homes Against Dangerous Tornadoes


Fox Blocks ICFs contribute towards a tornado-resistant design, protecting the integrity of Oklahoma's homes and their occupants. ICF walls provide a continuous load path and impact resistance, vital to resisting severe winds and flying debris of a tornado.

Fox Blocks are an ideal product for constructing a safe room to maximize a family's safety. ICFs provide builders with a quick and straightforward way to construct cost-effective, energy-efficient, durable, and fire-resistant homes in Oklahoma.

For more on why Fox Blocks ICFs are the perfect solution for building tornado-resistant, compliance to ICC 500 and FEMA P361, energy-efficient, fire-resistant, and durable homes in Oklahoma, don't hesitate to contact Fox Blocks professionals today.