What is a storm shelter?

How does a storm shelter work?

A storm shelter works by being stronger than the storm: FEMA's home designs use a 250 mph design wind speed and walls, roof and door that stop a 15-pound board flying at 100 mph. FEMA P-320 explains the design basis: “The safe room design wind speed used for these designs is 250 mph.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “Further, the debris impact resistance is based upon the 15-pound 2-inch × 4-inch board missile traveling horizontally at 100 mph (again, the most restrictive criteria for both tornado and hurricane hazards).” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “Further, the connections between all parts of the safe room must be strong enough to resist failure, and the walls, roof, and door must resist perforation by wind-borne debris.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “The intent of the designs is to enable the safe room occupants to survive an extreme windstorm with minor or no injuries, not for the safe room to remain completely undamaged.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29.

What does Ready.gov count as a storm shelter?

A storm shelter is a room or small structure built to keep the people inside alive through the extreme winds and flying debris of a tornado or hurricane. Ready.gov points people to a safe room built to FEMA criteria or a storm shelter built to the ICC 500 standard, and FEMA P-320 explains the terms: “Identify and practice going to a safe shelter such as a safe room built using FEMA criteria or a storm shelter built to ICC 500 standards.” Source: Ready.gov, read 2026-10-29. “Having a safe room for your home or small business can help provide near-absolute protection for you and your family or employees from injury or death caused by the dangerous forces of extreme winds.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “ICC 500 provides the minimum design and construction requirements for extreme wind storm shelters and has been incorporated by referenced standard into the 2009, 2012, and 2015 International Building Code (IBC) and International Residential Code (IRC).” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “Residential safe room. A safe room serving occupants of dwelling units and having an occupant load not exceeding 16 persons.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29.

Storm shelter for tornadoes

A tornado shelter at home can sit inside the house, be attached to it, or stand on its own outside, and it can be above ground, in-ground or in a basement. The Indiana Department of Homeland Security and FEMA P-320 describe the forms: “They can be an interior room, space within a building or an entirely separate structure.” Source: Indiana Department of Homeland Security, read 2026-10-29. “It can be either inside (within the building footprint) or outside (detached or adjacent to the existing building) and above-ground, in-ground, or in a basement.” Source: Indiana Department of Homeland Security, read 2026-10-29. “It is structurally independent of the larger building, but it provides the same wind and debris protection as a stand-alone safe room.” Source: Indiana Department of Homeland Security, read 2026-10-29. “In-ground safe rooms referred to in this publication are slightly different from basement safe rooms because they are buried underground and surrounded by soils on all sides.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29.

Storm shelter door

The door is part of the shelter's protection, so it has to meet the same wind and debris tests as the walls; an ordinary steel door does not. The Indiana Department of Homeland Security and FEMA P-320 set out what a shelter door must resist: “Residential safe room doors must be designed to resist a minimum wind speed of 250mph and be tested to resist the corresponding missile impacts and wind pressures.” Source: Indiana Department of Homeland Security, read 2026-10-29. “This means the doors must be subjected to 15-pound, 2-inch x 4-inch wood boards traveling at 100mph.” Source: Indiana Department of Homeland Security, read 2026-10-29. “The door assembly includes the door, hardware (locks and hinges), frame, and attachment devices used to anchor the door frame to the surrounding safe room wall.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “There is a common misconception that a steel “storm door” with three locks and three hinges can provide life-safety protection on a safe room, but it cannot.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “For example, inward-swinging doors are less likely to be blocked by debris, while outward-swinging doors provide more space within the safe room.” Source: Indiana Department of Homeland Security, read 2026-10-29.

How big should a storm shelter be?

In a one- or two-family home, the Indiana Department of Homeland Security lists a minimum of 3 square feet of usable floor area per person for a tornado safe room, and its fact sheet works an example of 3 bedrooms, 2 people per bedroom and 3 square feet each, or 18 square feet. Hurricane shelters need more room, as FEMA P-320 explains: “Safe rooms need to accommodate every person who belongs to a household.” Source: Indiana Department of Homeland Security, read 2026-10-29. “The amount of floor area per person that your safe room must provide depends partly on the type of windstorm from which the safe room is intended to protect you.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “The minimum sizing requirement set forth in ICC 500 for residential hurricane shelters is 7 square feet per occupant, while for community shelters 20 square feet per occupant is specified for standing or seated and wheelchair-bound occupants and 40 square feet per occupant for bed-ridden occupants.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “The safe room designs in this publication have a gross area of at least 64 square feet and a minimum wall length of 8 feet (for both tornado and hurricane hazards).” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29.

What is a storm shelter made of?

Storm shelters are built on site from the materials in FEMA's construction plans or bought as prefabricated units made of metal panels, concrete or fiberglass, and either kind needs a strong enough foundation. FEMA P-320 describes the materials: “These prefabricated units are constructed from a variety of materials, such as metal panels, concrete, fiberglass shells, and many more.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “A prefabricated safe room is a safe room that has been assembled off-site, typically in a manufacturing facility, and transported to the site where it will be installed.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “Typically, prefabricated safe room units include the entire safe room with the exception of the foundation.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “Steel doors commonly used in residential and commercial construction cannot withstand the impact of the wind-borne debris or wind pressures.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29.

How long should you stay in a storm shelter?

For a tornado the stay is usually short, while a hurricane shelter may be used for 24 hours or more, so plan for both and leave only when official updates say it is safe. FEMA P-320 and Ready.gov say: “Tornadoes are not typically long-lasting storms, so if you are relying on your safe room only for tornado protection, you will not need to stay in the safe room for as long as you would for a hurricane.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “When the safe room is intended to provide protection from storms such as hurricanes, which can last for 24 hours or more, the comfort of the occupants should be considered.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “Pay attention to EAS, NOAA Weather Radio, and local authorities for updated information.” Source: Ready.gov, read 2026-10-29.

What should you put in a storm shelter?

Keep an emergency supply kit in the shelter, including tools such as a crowbar, jack or spreader to open a door blocked by debris and another way to call for help. FEMA P-320, the Indiana Department of Homeland Security and Ready.gov advise: “You should also prepare an emergency supply kit and either keep it in your safe room or be ready to bring it with you if you need to evacuate your home.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “Additionally, remember that, after an extreme wind event, the egress from a safe room may be blocked.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “Therefore, tools to open or dismantle the door from the inside and an alternate means of communication should be kept in the safe room.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “The kit can include tools to open damaged doors such as a crowbar, jack or spreader.” Source: Indiana Department of Homeland Security, read 2026-10-29. “Prepare for a long-term stay at home or sheltering in place by gathering emergency supplies, cleaning supplies, non-perishable foods, water, medical supplies and medication.” Source: Ready.gov, read 2026-10-29.

Do storm shelters flood?

A storm shelter can flood if it is placed where water rises, so FEMA's rule is to keep shelters out of areas expected to flood and to check flood maps, storm surge areas and high water tables first. FEMA P-320 and the Indiana Department of Homeland Security say: “Safe rooms designed to protect you and your family or employees from a hurricane or tornado should not be built in areas expected to be flooded during a hurricane, thunderstorm, or other severe weather event.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “The protection from wind provided by safe rooms and shelters is quickly negated when people find themselves trapped and inundated by floodwaters.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29. “Per FEMA P-361, flood hazards should be considered when designing a residential safe room.” Source: Indiana Department of Homeland Security, read 2026-10-29. “Does my property have a high water table that could cause some types of safe rooms to flood?” Source: Indiana Department of Homeland Security, read 2026-10-29. “If you do not know whether your home or small business is in a storm surge area or other area subject to flooding, ask your local emergency management or floodplain management official.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29.

Is a basement a storm shelter?

A basement is the next best place in a home without a shelter, but it is not a storm shelter unless it was designed and built to FEMA P-361 criteria; strong tornadoes have collapsed basement walls. The Indiana Department of Homeland Security, Ready.gov and FEMA P-320 explain: “Some strong tornadoes have resulted in loss of floor framing, collapse of basement walls and death and injuries to individuals taking refuge in a basement.” Source: Indiana Department of Homeland Security, read 2026-10-29. “A basement may be the safest place to seek shelter in a home without a safe room, but the basement will not provide the same level of protection as a safe room unless it has been designed and constructed in accordance with the criteria in FEMA P-361.” Source: Indiana Department of Homeland Security, read 2026-10-29. “The next best protection is a small, interior, windowless room or basement on the lowest level of a sturdy building.” Source: Ready.gov, read 2026-10-29. “Basement safe rooms are in a basement but are not surrounded by soil on all sides.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29.

Are storm shelters safe?

A storm shelter built to FEMA criteria or ICC 500 gives what FEMA calls near-absolute protection, whether it is in-ground or above ground, while most ordinary homes do not protect people from tornadoes. The Indiana Department of Homeland Security and FEMA P-320 say: “Safe rooms are designed to provide near-absolute protection for occupants during severe thunderstorms and tornadoes.” Source: Indiana Department of Homeland Security, read 2026-10-29. “In-ground safe rooms provide inherent protection from windborne debris naturally afforded by the surrounding soil coverage.” Source: Indiana Department of Homeland Security, read 2026-10-29. “Above-ground safe rooms are required to be rigorously tested to ensure that they can also provide protection from windborne debris.” Source: Indiana Department of Homeland Security, read 2026-10-29. “Therefore, all properly constructed safe rooms offer life-safety protection if they are properly designed and constructed.” Source: Indiana Department of Homeland Security, read 2026-10-29. “Most homes, even new ones constructed according to modern building codes, do not provide adequate protection for occupants seeking life-safety protection from tornadoes.” Source: Federal Emergency Management Agency (FEMA), via the National Weather Service, read 2026-10-29.

Sources

• FEMA P-320, Taking Shelter from the Storm: Building a Safe Room for Your Home or Small Business (Fourth Edition) — Federal Emergency Management Agency (FEMA), via the National Weather Service; published 2014-12; read 2026-10-29.
• Residential Safe Room Fact Sheet — Indiana Department of Homeland Security; read 2026-10-29.
• Safe Room FAQ — Indiana Department of Homeland Security; read 2026-10-29.
• Tornadoes — Ready.gov; published 2026-06-02; read 2026-10-29.