When it comes to making the decision to building a storm safe room, you need the answer to one of the most frequently asked questions: “How do I determine if I really need a storm safe room to protect my family?” To answer this, consider the following questions:

• Is your home located in an area prone to severe storms that generate hail, high velocity straight winds, tornados, or hurricanes?
• How quickly can you reach a safe shelter during a severe storm with extreme high velocity winds?
• Do you want to provide this level of protection for you and your family?

If you answer, “Yes” to one or more of these questions, then you may want to seriously consider building a storm safe room in your home to protect you and your family from these threats.

Where Are Storm Safe Rooms Needed?

Anywhere in the world that is subject to extreme Storm and High Wind Events; homeowners should consider building a residential storm safe room. As noted in the following sections, wind hazards, such as those associated with tornadoes, hurricanes, and high velocity straight winds vary throughout the world. The decision to build a storm safe room will be based largely on the magnitude of the wind hazard in a given area and on the level of risk considered acceptable.

Understanding the Hazards

Potential Impact and Damage From a Tornado

Tornado damage paths over 50 miles long and over 1 mile wide have been reported. A good example of the destructiveness of tornadoes is the damage caused by the 67 tornadoes that struck Oklahoma and Kansas on May 3, 1999, which included many F4 and F5 tornadoes. This tornado outbreak resulted in 49 deaths and leveled entire neighborhoods.

Hurricanes

A hurricane is a type of tropical cyclone (the general term for all weather systems that circulate counterclockwise in the Northern Hemisphere over tropical waters) originating in the Atlantic Ocean, Caribbean Sea, or Gulf of Mexico. Around the core of a hurricane, winds can grow with great velocity. As the storm moves ashore, it can push ocean waters inland while spawning tornadoes and producing torrential rains and floods. On average, 10 tropical storms (6 of which become hurricanes) develop each year in the Atlantic Ocean. Approximately five hurricanes strike the United States mainland every 3 years; two of those storms will be major hurricanes Category 3 or greater on the Saffir-Simpson Hurricane Scale (Refer to Chart 1).

In the Western Pacific, hurricanes are called typhoons and affect the Pacific Islands, including Guam, American Samoa, and the majority of the Pacific Basin Islands. Historically in the Pacific Basin, typhoons have been classified by strength as either typhoons (storms with less than 150 mph winds) or super typhoons (storms with wind speeds of 150 mph or greater) rather than by the Saffir-Simpson Hurricane Scale.

What Is A Residential Storm Safe Room

Residential Storm Safe Rooms can take several forms:

• A room that normally serves another purpose (such as a bathroom, walk-in closet, storage room, walk-in pantry, or a combination of rooms) that has been strengthened (or "hardened") to resist wind forces and the impacts of windborne debris.
  
• A room specifically designed and constructed to serve as a storm shelter space only.
  
• An underground space created in a basement, beneath the floor of a house, in an attached garage, or cellar.
  
• Properly designed and constructed additions or in-residence storm safe rooms are preferable because they offer several advantages over exterior shelters. 
  
• The occupants of a house equipped with an internal storm safe room can reach the shelter without having to leave the house and risk exposure to high winds and wind blown debris, lightning, or other storm conditions.
  
• An internal storm safe room can be reached more quickly and easily.
  
• For those reasons, the occupants of a house equipped with an internal storm safe room are more likely to protect themselves adequately.

As mentioned earlier, a residential storm safe room can serve more than one purpose. Hardening (retrofitting) a bathroom, walk-in closet, or a combination of both to serve as a storm safe room makes more efficient use of space than building a room that serves as a storm safe room only. In smaller homes, providing for alternative storm safe room uses can be an important consideration.

Storm Safe Room Design

In general, residential storm safe rooms can be built onsite in a new home, as an addition, or retrofit in an existing home with materials recommended by the Federal Emergency Management Agency (FEMA), or can be prefabricated units delivered to the site and installed by the home owner or their contractor. A storm safe room can be built or installed almost anywhere in a house as long as it is anchored to the concrete pad/foundation, but it must be a "Room Within A Room." That is, it's walls and ceiling must be structurally separate from the rest of the house, so that even if the surrounding house is destroyed to the foundation, the storm safe room will remain intact thus protecting the occupants.

A storm safe room must not have any windows or be constructed in a flood or storm surge zone. It must be able to handle winds of 250 mph (which is close to the highest unofficially measured wind speed during Hurricane Iniki that struck Kauai in 1992). The size of a storm safe room will depend on the number of expected occupants. The storm safe room door should swing inward for easy egress of your family should the rest of the home collapse across the door face. The inward swinging steel door hardware should include (3) heavy-duty ball bearing hinges, (3) heavy-duty deadbolts with one-inch throws, and (1) locking latch handle with a one-inch throw.

Storm Safe Room Strength - Testing and Design

The goal of the storm safe room design and construction is to provide "Near Absolute Protection" from the forces of wind and debris during a storm with winds as high as 250 mph. A storm safe room that provides near-absolute protection will protect its occupants from death and injury; however the storm safe rooms exterior may be damaged by high winds or debris. As a result, repairs to the exterior walls and door of a storm safe room may be necessary after an extreme-wind event.

Clearly, to provide the desired level of protection, a storm safe room needs an extremely strong structure and anchors to resist high-wind forces and an extremely resistant envelope (walls, ceiling, and floor) to resist the impact of windborne debris. Storm safe room designs based on the results of the Texas Tech research typically call for stronger construction materials than designs for standard residential construction. Every storm safe room design and materials must meet or exceed FEMA’s minimum specifications. Storm safe rooms built according to the FEMA 320 minimum guidelines (no penetration of a 15-pound, 12-foot-long 2” x 4” board moving at 100 mph) and criteria are expected to provide near-absolute protection for their occupants.

Other Considerations

Although essential to successful performance, strength is not the sole consideration in storm safe room design and construction. A residential safe room must also be readily accessible, provide for the comfort of its occupants, and be equipped with emergency supplies.

Accessibility

Residential storm safe rooms should be constructed in such a way that they are readily accessible to all occupants of the home. The path to the storm safe room should not be blocked with furniture or stored items. Also, if the storm safe room is normally used for another purpose (a closet for example), care should be taken not to clutter the floor with anything that could restrict the usable storm safe room space. Special needs, such as those of vision or mobility-impaired users, should be considered when decisions are made concerning the type and location of the storm safe room.

Occupant Comfort

The primary goal of a residential storm safe room is to provide for the safety, not the comfort, of its occupants. The comfort of shelter occupants will depend largely on the amount of space provided per occupant and adequate lighting, water, food, and toilet. The amount of space required per person depends on the duration of occupancy. For this reason, the required space differs between storm safe rooms intended for tornado protection and those intended for hurricane protection. Historical data indicate that a tornado storm safe room will typically have an average maximum occupancy time of 2 hours. By contrast, a hurricane storm safe room will have an average occupancy time of 24 to 78 hours.

FEMA’s recommended minimums for occupant space are 5 square feet per person for tornado storm safe rooms and 10 square feet per person for hurricane storm safe rooms. Note that these square footage figures are minimums; larger amounts of space are required for special situations. For example, the 5-square-foot minimum for tornado storm safe rooms assumes that the occupants will be standing for the duration of the event. Larger amounts of space are required for seated occupants and those with special needs, such as occupants confined to a wheelchair.

Adequate supplies of water are essential for both tornado and hurricane storm safe rooms. Food and water should be provided in hurricane storm safe rooms, but is not a major consideration in tornado storm safe rooms, because of the short duration of use. All residential storm safe rooms should be equipped with emergency supplies, including drinking water, flashlights, fire extinguishers, first-aid kits, radios (preferably weather radios with extra batteries), and a signaling device (such as an air horn or Police Whistle).

New Construction vs. Retrofitting

An additional consideration is whether a storm safe room will be built as new or retrofit construction. Building a storm safe room as a part of a new home or as an addition may be more efficient than retrofitting (modifying an existing home to meet specific design requirements).