Arkansas Shelter/Safe Room Program

• This state program assists Arkansas home-owners who choose to install a shelter or safe room on their property. The program covers up to 50 percent of the cost and installation not to exceed$1,000. The statewide rebate program applies to persons who have installed safe rooms or in-ground shelters at their primary residence on or after Jan. 21, 1999. Safe room installation must meet FEMA Publication 320 or National Performance Criteria for Tornado Shelters standards.

Arkansas Tornadoes by County

Tornadoes in Arkansas

• The state has experienced 1,681 tornadoes between 1950 and 2007,with 239 tornadoes that were F3 and higher.

• State of Arkansas ranked fourth in the nation in deaths and fifth in injuries.

• Average of nearly 30 tornadoes

annually.

Tornadoes in Arkansas

• On the afternoon of Feb. 5, 2008 a weather system moved across the State of Arkansas, resulting in severe thunderstorms, tornadoes and flooding across the state. According to the National Weather Service, this was the deadliest severe weather event in the state since March 1, 1997. One of the tornadoes tracked 123 miles, which is the longest track on record in Arkansas since 1950. The tornadoes claimed the lives of 13 people.

Map showing the 2008 tornado track

Safe rooms in residences

• A residential safe room costs anywhere between $3,000 and $10,000. it is mandatory for the safe room to meet the requirements established by FEMA 320 or meet the National Performance Criteria for Tornado Shelters.

Safe Rooms in Residences

• A safe room is a reinforced room built in a new or existing above-ground structure that can provide protection during storms. A safe room is often a closet or

bathroom that has been modified to provide occupant protection in the event of a tornado

Commercially-Manufactured Shelters

• An alternative to the in-home safe room is a commercially-manufactured shelter that, depending on the type, can be installed above-ground, below ground or partially below-ground. In-ground safe rooms have no state regulations; however, they must meet local codes. They cost between $1,200 and $4,500. They must be constructed of a waterproof material, properly

ventilated, and contain doors that meet the National Performance Criteria for Tornado Shelters.

Commercially-Manufactured Shelters

Continuous Load Path

• Structural systems that provide a continuous load path are those that support all loads acting on a building: laterally and vertically (inward and outward, upward and downward). A continuous load path can be thought of as a “chain” running through a building. The “links” of the chain are structural members, connections between members, and any fasteners used in the connections (e.g., nails, screws, bolts, welds, or reinforcing steel).

Continuous Load Path

LOAD PATH FAILURE

Wood 2x4 launched at 100 mph

Windborne Debris (Missile) Impacts

Windborne Debris (Missile) Impacts

• Walls, doors, and other surfaces inclined 30 degrees or more from the horizontal are tested at the design missile speed of 100 mph.

• Those surfaces inclined 30 degrees or less from the horizontal are tested at 67 mph.

Debris Impact Criteria

• Underground shelters or portions of them with less than 12 inches of soil cover should be able to meet the same

criteria as if the surfaces were exposed.

Impact Resistance

• Wood Systems: Must be attached using AFG-01 adhesive and #8 wood screws penetrating at least 11/2” and spaced not more than 6” apart.

• Sheet Metal: 14-gauge steel sheet can resist perforation only when it is used as the last layer on the non-impact face on the interior (shelter side) of the wall. If sheet metal alone is relied on for missile impact protection, it should be 12 gauge or heavier.

• Composite Wall:6- and 8-inch-thick concrete masonry unit (CMU) walls that are fully grouted with

concrete and reinforced with #4 reinforcing steel (rebar) in every cell can withstand the impact of a 15-lb 2x4 wood

Wood Systems

Sheet Metal Systems

Composite Wall Systems

Composite Wall Systems

Reinforced Concrete Wall

Roof Systems

• Based on the observed behavior of roof specimens, it is believed that roof designs that incorporate a uniform thickness (i.e., flat slab of at least 4” with #4 rebar) provide a more uniform level of protection from large debris impacts, than a waffle slab, or ribbed slab.

Single-Door Systems Less Than 36 Inches Wide

• Steel doors with exterior skins of 14 gauge or thicker. The minimum hardware reinforcement should be 12 gauge.

• Lighter-skinned steel doors may be used with modification. The modification is the addition of a 14-gauge steel sheet to either side of the door using 1/4X1 ¼ inch self-tapping screws 6” OC.

• No wood door has ever passed the missile test.• However, by adding a layer of 14 gauge steel

sheathing on either side the door will pass the test.

Door Frames

• Sixteen-gauge steel door frames in either a welded or knockdown style are known to be adequate to carry design wind and impact loads on a single door

Welded Door FrameKnock Down Style Frame

Door Hardware

• Steel doors with supplemental latching mechanisms near the top and the bottom are required to carry design wind loads and to prevent an inward-swinging door from being knocked open with a well-placed missile.

• Three latching mechanisms and 3 hinges are required (6 pts of attachment) so that, if debris impacts close to one and destroys it, two will be left to carry the wind loads.

Door Hardware

• Doors with two additional mortised, cylindrical dead bolts (with solid 1/2-inch-thick steel throw bolts with a 1-inch throw into the door jamb) above and below the original latch would meet the requirement of the wind pressure and missile impact tests. Deadbolts that are operable from the inside shall be keyed from the outside.

Door Systems

• A three-point latching system operated with a single-action lever, built with heavy duty steel with a 1” solid bolt with a 1” throw, that activates two 1 3/8” solid hook-bolts will also pass the missile test

Windows

• Testing indicates that glass windows in any configuration are undesirable for use in tornado shelters. It is therefore recommended that glazing units subject to debris impacts not be included in shelters or that they be covered with material that meets the standards for doors.

Ventilation

• Passive ventilation is required for all residential shelters. This is defined as the non-powered air flow into and through the shelter envelope by way of openings that provide air for breathing. Openings must be a minimum of 4” OD and be protected to prevent intrusion of wind-borne debris.

Flood Hazard Considerations

• The lowest floor of the shelter must be elevated 1 foot above the base flood elevation from any of the flooding sources. All utilities or services provided to the shelter must be protected from flooding as well.

• Don’t site shelters where the possibility of flooding is present.

Other Hazard Considerations

• Hazardous materials

• Power lines

• Gas mains

• Fire

References• FEMA Pub. 361 ( Design and Construction

Guidance for Community Shelters)• FEMA Pub. 320 ( Taking Shelter from the

storm: Building a safe room in your home)– To request a copy of this publication, call 1-

800-480-2520

• National Performance Criteria For Tornado Shelters

• Association Standard for the Design, Construction, and Performance of Storm Shelters