✅ Quick Answer: How Much Space Do I Need in a Storm Shelter?
FEMA recommends at least 3 square feet per person for a tornado shelter, 7 square feet per person for a hurricane shelter, and 10 square feet for each person in a wheelchair. For example, a family of four needs at least 12 square feet to shelter from a tornado, which a 4′ × 4′ shelter (16 sq ft) provides. Pets, supplies, and extra room for comfort usually push that number higher, and benches or storage inside the shelter reduce usable floor space.
| What needs space | Minimum floor space |
|---|---|
| Each person (tornado) | 3 sq ft |
| Each person (hurricane) | 7 sq ft |
| Each wheelchair user | 10 sq ft |
| Each pet (small to XL) | 2-12 sq ft |
| Supplies footprint | 3 sq ft |
| Portable air conditioner (example) | 4 sq ft |
Note: People and wheelchair figures are FEMA guidelines. Pet, supplies, and air conditioner figures are planning estimates used by the Storm Shelter Calculator.
When I began researching our storm shelter, one of the questions I asked was, “How much space do I need in a storm shelter?”I knew we needed enough space for our four family members who live in the house, plus our oldest son, daughter-in-law, and grandchild, who live nearby and visit often. I also knew we needed enough room to quickly roll my disabled son into the shelter without wasting precious seconds. We also needed room for our two small dogs, water, emergency supplies, and other comfort items. Considering our space needs, we also didn’t want to feel cramped.
How Much Space Do I Need In A Storm Shelter?
Everyone has different requirements when determining the space needs of a storm shelter. For instance, how many people will it need to protect? Does anyone you need to protect have mobility challenges that may require extra space? Do you have pets? If so, how many and are they small or large? You need to take their size into account. What about additional space for essential and optional supplies and equipment?
It is also important to consider where you will install your storm shelter and how much space you have available.
If you’re still early in your shelter research and want to understand the larger framework for choosing the right storm shelter, including safety standards, design factors, and key decision-making criteria, then start with my Storm Shelter Buying Guide before estimating space requirements.
Storm Shelter Space Guidelines
The Federal Emergency Management Agency (FEMA) makes specific recommendations in FEMA P-320 (Taking Shelter from the Storm) on floor space allocation for residential storm shelters (one- and two-family dwellings).
Sheltering for a Tornado:
Since people typically shelter from a tornado for a short period of time (15-30 minutes is common), individual comfort is not the primary concern. According to the FEMA guidelines, a storm shelter that provides at least 3 square feet of floor space per individual is sufficient for those sheltering from a tornado.
Sheltering for a Hurricane:
People may seek shelter for 24 hours or more during a hurricane. Therefore, individual comfort becomes a more critical consideration. FEMA recommends a minimum of 7 square feet per individual.
Other Space Considerations:
FEMA recommends that individuals in wheelchairs have at least 10 square feet of space in either situation (sheltering from tornadoes or hurricanes).
It is important to note that FEMA bases the guidelines on usable floor space. So, a storm shelter that is 8′ long and 6′ wide would yield 48 square feet of usable floor space. If the shelter includes a 12″ storage bench/seat along the 6′ wall, that removes usable space. In this example, there would be 42 square feet of usable floor space since the bench/seat will consume 6 square feet.
Space Calculation Examples
So, how do these recommended numbers translate into storm shelter size? Here are a few example calculations.
Family of Five
5 people x 3 square feet per person = 15 square feet, minimum. A 4′ x 4′ shelter will provide 16 square feet of floor space, which would be sufficient. However, if you have pets or plan to include supplies, you will need additional space. So, a 6′ x 4′ shelter, which will provide 24 square feet of space, may be more preferable.
Family of Four
4 people x 3 square feet per person = 12 square feet, minimum. In this case, a 4′ x 4′ shelter provides 16 square feet of space and will meet the minimum requirement. As in the prior example, pets or supplies will increase space needs. In this case, a 4′ x 4′ shelter may work fine, but a 6’ x 4’ shelter may be a better fit.
Family of Seven (One in a Wheelchair)
Okay, this is the specific scenario I planned for our family. My wife and I, plus two of our three kids that were living at home at the time. One of our kids is disabled and in a wheelchair. Plus, my oldest son, his wife, and their child also live in the area, and we see them regularly. Since they live nearby, I also planned for them when deciding on our shelter.
So, 6 people x 3 square feet per person, plus 1 person x 10 square feet = 28 square feet, minimum. We also have two small dogs, and I planned to purchase additional supplies and equipment (including a portable air conditioner). I assumed 3 square feet for the two dogs plus another 7 square feet for the portable A/C and additional supplies. So, I needed a minimum of 38 square feet. A 5′ x 8′ shelter (40 square feet) would technically meet my needs, and that’s the size I had in mind when we started visiting storm shelter providers.
Best Way to Determine the Size Needed? Try Them Out!
Armed with the square feet requirements, I initially thought a 5′ x 8’ shelter (40 square feet) would meet my family’s needs. Technically, according to FEMA guidelines, it would. However, I also knew we needed to try several shelters to see how well they “fit.” So, we visited numerous storm shelter companies to get a feel for different sizes and configurations that would meet our minimum space requirement of 38 square feet.
In the end, even though a shelter that was 40 square feet would meet the requirement, it just felt cramped. In the end, we bought a shelter that was just slightly larger at 6′ x 8′, which gave us 48 square feet. It has a 14″ lockable storage bench/seat along the 6′ wall that consumes just slightly over 7 square feet. This bench locker stores many of our supplies and it also houses a battery bank that provides backup power. Plus, the door configuration met our needs, allowing quick entrance and maneuverability of my son’s wheelchair.
I only knew all of this because we took the time to visit several manufacturers to “try out” different storm shelters.
My Recommendation
Determine the number of people you need to protect as a starting point. Then, use my storm shelter calculator to estimate both the recommended minimum and comfortable size to meet your specific needs. But, most importantly, try out different shelter sizes! Visit several storm shelter companies and tour the shelters. This is the best way to learn about the types of shelters, their sizes, their configurations (e.g., door placement), and the options available.
What other factors should be considered when determining the storm shelter size for your home? Add a comment below or contact me directly!