ICF Tornado Safe Rooms or Shelters for Homes and Small Businesses

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To ensure a tornado safe house that best protects the occupants during a tornado event, the Federal Emergency Management Association (FEMA) highly recommends a tornado safe room or shelter, built according to FEMA guidelines.

A residential safe room built with Fox Blocks insulated concrete forms (ICF) meets and exceeds the criteria for a FEMA residential safe room design for a continuous load path and impact resistance. In the event of a dangerous tornado, a safe room built with ICF can ensure the safety of a home’s occupants.

The Benefits of FEMA Approved Safe Rooms or Storm Shelters


Tornado safe rooms are crucial in the United States (U.S.) where an average of 1253 tornadoes occur yearly, creating wind speeds up to 200 mph or more. The impact of tornadoes is catastrophic and kills annually about 60 people, many from flying or falling debris. The majority of tornado fatalities are located either in a mobile or permanent home. Safe rooms are vital to the protection of a home’s occupants during a tornado event.

A further advantage of a safe room is it increases a home’s value. In fact, a report by Professor Kevin Simmons, an economist with Austin College and the Federal Alliance for Safe Homes, found that safe rooms increase a home’s worth by about $4,200, or on average of 3.5 percent.

Designing and building a tornado shelter or safe room, as specified in FEMA P-361 and FEMA P-320, will create a tornado safe house that provides maximum protection to a home's occupants during a tornado emergency.

Untangling the Guidelines and Standards for Safe Room Design

ICC-500 - The Standard for Design and Construction of Safe Rooms

The ICC-500 is the International Code Council’s and the National Storm Shelter Association’s (NSSA) standard (ICC/NSSA) for the construction and design of storm shelters (safe rooms). The 2014 ICC-500 is the current ICC/NSSA standard for construction and design of residential and community storm shelters.

ICC-500 - The Referenced Standard for Building Safe Room Used by the IBC, IRC, and FEMA

Since 2009, the International Building Code (IBC, Section 423) and the International Residential Code (IRC, Section R323) have utilized the ICC-500 as their reference standard for building storm shelters. FEMA also uses ICC-500 as a referenced standard for building safe rooms and storm shelters. However, the FEMA guidelines are considered more conservative than the IBC and IRC requirements.

Builders and architects of safe rooms can find the FEMA guidelines in FEMA P-320 (Taking Shelter from the Storm: Building a Safe Room for Your Home or Small Business) and FEMA P-361 (Safe Rooms for Tornadoes and Hurricanes: Guidance for Community and Residential Safe Rooms).

The ICC-500 is the reference standard used by the IBC, IRC, and FEMA for the design and construction of safe rooms. Residential safe rooms designed to FEMA guidelines provide occupants of small businesses or homes the best safety against high winds and flying debris during a tornado event.

Building a Tornado Safe House with a FEMA Safe Room

A residential safe room is a solid space designed to meet FEMA specifications. A FEMA safe room provides the occupants of a home or small business near-total protection in severe weather events, including tornadoes. T

The construction and design of a residential safe room must follow the guidelines described in FEMA P-320 and FEMA 361. Critical components of a FEMA residential safe room are a strong continuous load path, and resistance to windborne debris, overturning, and uplift.

A Continuous Load Path is Key to a Residential Safe Room Design


A strong continuous load path is key to holding the roof, walls, and foundation of a safe room together during a powerful wind event. A continuous load path ensures that when wind loads attack the roof, the loads will transfer to the shear walls.

The shear walls of the safe room are the essential elements of the continuous load path that block the lateral-loads (horizontal wind forces). The walls must keep their integrity and have the strength to support the roof, while concurrently moving the loads to the foundation. Ultimately, the wind loads must move from the foundation to the ground.

A superb product for a residential safe room is Fox Blocks, which are FEMA approved. Fox Blocks reinforced concrete walls have the continuous load path required to resist severe wind events during tornadoes. The Fox Blocks Wall System is also durable and has the strength to support a roof.

Residential Safe Rooms Must Protect Against Flying Debris


The walls, roof, and doors of a residential safe room must resist the impact and penetration of flying debris during a tornado.

  • A safe room roof must withstand the impact of a 15-pound 2-inch X 4-inch shot at 67 mph.
  • Safe room doors should have documented proof that they are compliant with the most current version of FEMA P-361 and FEMA P-320 or the ICC 500 for tornado wind speed of 250 mph.
  • Safe room walls must resist the impact of a 15-pound 2-inch X 4-inch shot at 100 mph

The whole envelope of a residential safe room must protect the shelter’s occupants from flying debris during a dangerous tornado.

An ideal choice for a FEMA safe room is insulated concrete form (ICF) Fox Blocks. Fox Block walls resist damage from flying debris traveling over 100 mph. Fox Blocks are the best protection from windblown debris to occupants in a safe room during a tornado event.

Safe Rooms Must Resists Uplift and Overturning

It is essential to a residential safe room to anchor its foundation so to resist overturning and uplift as it receives the wind loads from of the walls. The anchoring and design of the slab-on-grade foundation must follow the guidelines in FEMA P-361, as defined by the ICC-500 (Section 308.1.1.2). During life-threatening wind events, the foundation of a residential safe room must resist uplift, overturning, and sliding forces.

When designed and built according to FEMA guidelines, a tornado safe room or shelter, for a home or small business, will create a space for the occupants that provides maximum protection during tornadoes. A residential safe room constructed with ICF meets and exceeds the criteria for a FEMA residential safe room design for a continuous load path and impact resistance.

Please visit Fox Blocks for more information on building a safe room for a tornado safe house.