News Article

Residential Safe Room Design

A res­i­den­tial safe room pro­tects the occu­pants of a home or small busi­ness from the high wind forces of a tor­na­do or hur­ri­cane. Safe rooms are essen­tial in the Unit­ed States where an aver­age of 1,253 tor­na­does occur year­ly, cre­at­ing wind speeds of 200 mph or more. Between the years of 1991 and 2010, Texas alone expe­ri­enced an annu­al aver­age of 155 tor­na­does, more than any oth­er state. The impact of tor­na­does and hur­ri­canes is dev­as­tat­ing. The Nation­al Ocean­ic and Atmos­pher­ic Admin­is­tra­tion (NOAA) reports that tor­na­does cause an aver­age of 60 – 65 fatal­i­ties and 1,500 injuries each year. In 2017, Hur­ri­canes Har­vey and Irma took 143 lives. CNN reports that 500 peo­ple have died as a result of Hur­ri­cane Maria, with 113 peo­ple still miss­ing. An added ben­e­fit of a safe room is it increas­es a home’s val­ue. In fact, a study by Pro­fes­sor Kevin Sim­mons, an econ­o­mist with Austin Col­lege and the Fed­er­al Alliance for Safe Homes con­clud­ed safe rooms increase a home’s val­ue by approx­i­mate­ly $4,200, or on aver­age 3.5 per­cent. Res­i­den­tial safe rooms are a good invest­ment and essen­tial for pro­tect­ing the occu­pants of a home or small busi­ness from dis­as­ter dur­ing high wind events, like tor­na­dos and hur­ri­canes.

Design Standards and Guidelines for Residential Safe Room Design

The ICC-500 is the Inter­na­tion­al Code Council’s and the Nation­al Storm Shel­ter Asso­ci­a­tion (NSSA) stan­dard (ICC/NSSA) for the Design and Con­struc­tion of Storm Shel­ters (safe rooms). The 2014 ICC-500 is the most cur­rent ICC/NSSA stan­dards for con­struc­tion and design and con­struc­tion of res­i­den­tial and com­mu­ni­ty storm shel­ters. Since 2009, the Inter­na­tion­al Build­ing Code (IBC, Sec­tion 423) and the Inter­na­tion­al Res­i­den­tial Code (IRC, Sec­tion R323) have uti­lized ICC-500 as their ref­er­ence stan­dard for build­ing storm shel­ters.

The Fed­er­al Emer­gency Man­age­ment Asso­ci­a­tion guide­lines are found 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. Both FEMA doc­u­ments use ICC-500 as a ref­er­enced stan­dard, how­ev­er, the FEMA stan­dards for safe rooms are con­sid­ered slight­ly more con­ser­v­a­tive than the stan­dard for ICC-500 storm shel­ters. The ICC-500 is the ref­er­ence stan­dard for the design and con­struc­tion of storm shel­ters that will pro­tect the occu­pants of a busi­ness or home dur­ing wind storm events. Res­i­den­tial safe rooms designed to FEMA guide­lines offer occu­pants of homes and small busi­ness­es near-absolute pro­tec­tion” against severe wind events.

Designing an ICC-500 Residential Storm Shelter

An ICC-500 res­i­den­tial storm shel­ter is a sol­id struc­ture designed to meet IRC/ICC spec­i­fi­ca­tions and pro­vide the occu­pants of a home a degree of life safe­ty in extreme weath­er events, includ­ing tor­na­does and hurricanes.The design and con­struc­tion of an ICC-500 res­i­den­tial storm shel­ter must fol­low the guide­lines spec­i­fied in the ICC-500 stan­dard (here is a free sum­ma­ry pro­vid­ed by FEMA). Key ele­ments of an ICC-500 res­i­den­tial storm shel­ter are a strong con­tin­u­ous load path, and resis­tance to over­turn­ing, uplift, and wind­borne debris.

Residential Storm Shelter Design must have a Continuous Load Path

A strong con­tin­u­ous load path is crit­i­cal to hold­ing the roof, walls, and foun­da­tion of a res­i­den­tial storm shel­ter togeth­er dur­ing an extreme wind event. The shear walls1 of the storm shel­ter is the pri­ma­ry com­po­nent of the con­tin­u­ous load path that com­bats the lat­er­al-loads (hor­i­zon­tal wind forces). High winds trav­el­ling over the roof of the storm shel­ter cre­ates uplift forces that pull on the walls. Winds hit­ting the wind­ward side of the safe room impart lat­er­al push­ing forces on the wall and the move­ment of air around the lee­ward side of the struc­ture caus­es suc­tion pulling on the walls in the direc­tion of wind trav­el. The walls of the storm shel­ter must main­tain their integri­ty and trans­fer all of these loads to the foun­da­tion. The foun­da­tion must also be designed to resist any over­turn­ing of the struc­ture due to the com­bined forces of the wind.

The Bau­tex™ Block Wall Sys­tem is an excel­lent prod­uct for a res­i­den­tial storm shel­ter. The steel rein­forced con­crete poured inside the Bau­tex Blocks have the con­tin­u­ous load path required to resist extreme wind events dur­ing tor­na­does and hur­ri­canes. Bau­tex Blocks meet the ICC-500 guide­lines in areas with max­i­mum wind speeds up to 225 mph. Essen­tial to the design of a res­i­den­tial storm shel­ter is a con­tin­u­ous load path. Cru­cial to the con­tin­u­ous load path of a res­i­den­tial storm shel­ter is a strong wall sys­tem that can also sup­port the roof, like the Bau­tex™ Block Wall Sys­tem.

Residential Storm Shelter Design Resists Overturning and Uplift

The foun­da­tion of a res­i­den­tial storm shel­ter must be anchored so to resist over­turn­ing and uplift as it receives the wind loads from of the walls. The design and anchor­ing of the foun­da­tion must fol­low the guide­lines in the ICC-500 stan­dard (Sec­tion 308.1.1.2) which man­dates that the design of slab-on-grade foun­da­tions be designed for the applic­a­ble loads and must at a min­i­mum be 3.5 inch­es thick, con­tain steel rein­force­ment, and take into account the pres­ence of slab joints” . Dur­ing severe wind events, the foun­da­tion of a res­i­den­tial safe room must resist over­turn­ing, uplift, and slid­ing forces.

Residential Storm Shelters Must Protect Against Flying Debris

The roofs, walls, and doors of a res­i­den­tial storm shel­ter must resist the impact and pen­e­tra­tion of fly­ing debris dur­ing a severe wind event. The roofs of a safe room must be built to resist the impact of a 15-pound wood 2×4 shot at 67 mph. The doors of a safe room 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. Walls of an ICC-500 storm shel­ter must be built to resist the impact of a 15-pound wood 2×4 shot at 100 mph. The entire enve­lope of a res­i­den­tial safe room must pro­tect the room’s occu­pants from fly­ing debris dur­ing hur­ri­canes and tor­na­does.

The Bau­tex Block Wall Assem­bly resists the impact and pen­e­tra­tion of fly­ing debris dur­ing a severe wind event, which makes the Bau­tex Block an ide­al mate­r­i­al choice for a res­i­den­tial safe room. Specif­i­cal­ly, Bau­tex insu­lat­ed con­crete block has the mass and strength to resist the impact to wind-dri­ven debris at speeds more than 100 mph. Also, 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 res­i­den­tial safe room pro­tects the occu­pants of a home or small busi­ness dur­ing severe wind events. A res­i­den­tial safe room con­struct­ed with Bau­tex Blocks meets and exceeds the cri­te­ria for a FEMA res­i­den­tial safe room design for con­tin­u­ous load path and impact resis­tance. Vis­it Bau­tex Block Wall Sys­tems for more infor­ma­tion on res­i­den­tial safe room design.

1Shear walls are a struc­tur­al sys­tem that pro­vides lat­er­al resis­tance to a build­ing home, safe room, etc.