Building a School Safe Room with Bautex Blocks

Tornado-resistant safe rooms are crucial in the United States where an average of 1253 tornadoes occur annually, producing wind speeds up to 200 mph or more. Safe rooms in schools are espe­cial­ly important because our children count on us to protect them. In 2013, the need for safe rooms in schools became trag­i­cal­ly apparent. A tornado with winds of 210 mph hit and destroyed two ele­men­tary schools in Moore, Oklahoma — killing seven children. Struc­tur­al defi­cien­cies in the schools were blamed for the buildings col­laps­ing. Tornado-proof safe rooms in the schools could have prevented this loss of life.

Since 2015, the Inter­na­tion­al Building Code (IBC) and the Inter­na­tion­al Existing Building Code (IEBC) have required storm shelters (safe rooms) in K‑12 school buildings (Edu­ca­tion­al Group E). These spec­i­fi­ca­tions apply to schools with at least 50 occupants and located in areas with shelter design wind speeds of 250 mph, as specified by the Inter­na­tion­al Code Council (ICC) ICC-500, Figure 304.2(1). The ICC-500 is the ICC/​NSSA standard for the design and con­struc­tion of storm shelters. Its purpose is to protect the occupants in buildings from dangerous winds and flying debris caused by hur­ri­canes and tornados. The IBC along with the Inter­na­tion­al Res­i­den­tial Code (IRC), site the ICC-500 as the governing standard for the design and con­struc­tion of storm shelters. There are several specific features of a safe room required by the ICC-500.

  • The safe room must be large enough to hold all the occupants of the building 
  • The safe room must withstand a direct hit from a tornado with wind speeds of 250 mph
  • A safe room’s walls must withstand a debris missile impact of a 15-pound, 2‑inch X 4‑inch shot at 100 mph
  • Roofs of a safe room must withstand an impact of a 15-pound, 2‑inch X 4‑inch shot at 67 mph

Besides a solid outer structure, the design of a safe room must include several other features.

  • HVAC and MEP systems
  • Toilets and hand wash systems which are inde­pen­dent of city systems. 
  • Proper ven­ti­la­tion and illumination

The Federal Emergency Man­age­ment Asso­ci­a­tion guide­lines (FEMA P‑320 and FEMA 361), which also use ICC-500 as a ref­er­enced standard, also specify require­ments for a safe room. The FEMA guide­lines, however, are con­sid­ered slightly more con­ser­v­a­tive than the IBC and IRC requirements. 

  • Safe rooms must be anchored to the build­ing’s foun­da­tion to resist over­turn­ing and uplift
  • A safe room must have a con­tin­u­ous load path that resists lateral and uplift loads during high winds
  • The roof, openings, and walls of a safe room must resist per­fo­ra­tion by windborne debris
  • The walls of the safe room are inde­pen­dent of the rest of the building

Constructing a School Safe Room

A school safe room must be designed and built in com­pli­ance with the standards mandated by the IBC, IEBC, and FEMA. Safe rooms must maintain their integrity during the high wind forces of a tornado or hurricane. Also, the materials used for the entire envelope of the safe room must combat struc­tur­al damage by windborne debris. Finally, the safe room(s) must be large enough to hold everyone in the school and be located either within the school or no more than 1000 feet from at least one of the school’s exterior doors. A safe room can be an assigned single use space or a multiple use space like a gymnasium, cafeteria, or other large community space. Safe rooms built to codes and standards will provide students, teachers, and others the best pro­tec­tion during a dangerous tornado or hurricane event.

Components in the Design of a School Safe Room

A school save room designed with a strong con­tin­u­ous load path should maintain its struc­tur­al integrity during a severe wind event. A con­tin­u­ous load path ensures that the con­nec­tions between the roof, walls, and foun­da­tion will have the strength to resist the vertical and lateral loads during severe weather. The com­po­nents of a safe room must also resist the impact of wind-borne debris, flood loads, and buoyancy forces. 

The Walls of A School Safe Room

The walls are the main component of the safe room that resists the lateral-loads (hor­i­zon­tal wind forces). They also are bearing/​shear walls. The wind forces on the roof, transfer to the walls. The walls then transfer these forces to the foun­da­tion, and ulti­mate­ly to the ground. The walls must also have the strength to support the roof. An ideal product for safe room con­struc­tion is the Bautex™ Block Wall Assembly. The Bautex Blocks have the con­tin­u­ous load path needed to resist the strongest winds. Bautex Blocks meet the Federal Emergency Man­age­ment Agency FEMA 320 and FEMA 361 guide­lines in storm zones with wind speeds up to 250 mph.

Foun­da­tion and Anchoring Criteria for Safe Rooms

The foun­da­tion of a safe room receives the loads from of the walls and directs the forces into the ground. The design and anchoring of the foun­da­tion must follow the criteria in FEMA P‑361, as specified by the ICC-500. The ICC-500 (Section 308.1.1.2) mandates that the design of slab-on-grade foun­da­tions be in accor­dance with ICC-500. During extreme wind events, the foun­da­tion of a safe room must resist uplift, over­turn­ing, and sliding forces. Slabs must have a minimum thickness of 3.5‑inches with a minimum of 6‑inch X 6‑inch, W 1.4‑inch X W 1.4‑inch welded wire rein­force­ment. Or the slabs can have number four bars spaced at a maximum of 18-inches on center in two per­pen­dic­u­lar directions.

The Roof and Doors of a Safe Room

A safe room roof must be securely and suf­fi­cient­ly connected to the walls so as to withstand the wind forces of a tornado. Roofs of a safe room must be built to resist the impact of a 15-pound 2‑inch X 4‑inch shot at 67 mph. The roofs must also be imper­me­able to water. Rein­forced concrete roofs, like concrete walls, can withstand the wind forces, attacks by debris caused by a tornado, and when properly installed are waterproof. 

The doors of a safe room must withstand wind forces and flying debris. Doors used in safe rooms 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. 

A Safe Room Must Protect Against Flying Debris During High Wind Events

The entire envelope of school safe room must protect the room’s occupants from flying debris during tornadoes and hur­ri­canes. A study by Texas Tech Uni­ver­si­ty compared the effect of wind-generated debris against walls con­struct­ed of plywood, metal com­bi­na­tions, finished concrete masonry unit (CMU), rein­forced concrete, and others. The study proved that concrete walls for a safe room are the best choice for pro­tect­ing occupants from flying debris. Bautex Block Wall Assembly’s insulated concrete block has the strength and mass to combat the impact to wind driven debris at speeds greater than 100 mph. The Bautex Blocks meets or exceeds the following ICC-500 FEMA standards for debris impact.

  • Series 1 FEMA 320361 Bautex Block Panel with Brick Veneer.
  • Series 2 FEMA 320361 Bautex Block Panel with CMU Block Veneer.
  • Test pro­jec­tile 15 lb. wooden 2‑inch X 4‑inch propelled at 100 mph.

A safe room is crucial for the pro­tec­tion of those that work and study in a school, par­tic­u­lar­ly in tornado-prone regions like Tornado Alley. After the announce­ment of a tornado warning, occupants of a school have on average 13 minutes to seek shelter from the up to 250 mph winds and the large flying debris caused by a tornado. A school safe room con­struct­ed with Bautex Blocks will protect children and teachers in a school by with­stand­ing the winds and dangerous debris of the strongest tornado.