Storm shelters are necessities for anyone who lives in an area of the country that’s prone to severe weather, and can be the difference between life and death. You must build the structure correctly, though, to keep yourself safe. Read how to build an underground or above-ground storm shelter, or how to hire professionals to build one, in our guide below, and watch the video above for tips from plumbing and heating expert Richard Threthewey.
Is Building a Storm Shelter a DIY Job?
Building a storm shelter is not typically a do-it-yourself task unless you have experience in constructing storm shelters. We recommend hiring professional builders who can safely complete the job.
Understanding Storm Shelter Basics
Storm shelters, which are also known as safe rooms, are hardened structures that can withstand extreme weather and protect occupants from flying debris. You can retrofit a storm shelter into your existing home or build one as a standalone structure in the backyard.
Types of Storm Shelters
There are several ways you can incorporate a storm shelter into your property, including those below.
- Basement shelters
- Freestanding above-ground structures
- Garage installations
- Interior room retrofits, such as closets or bathrooms
- Outdoor underground shelters
The best choice for your property depends on your home’s layout, local weather patterns, and personal preferences. We recommend above-ground options for areas that are prone to flooding.
Size Recommendations
The size of the storm shelter in which you should invest depends on how many people must fit, and what types of storms are common in your area. Tornado structures should have a minimum of 3 to 5 square feet per person, while hurricane structures should have 7 to 10 square feet per person, according to the Federal Emergency Management Agency’s guide on safe rooms for tornadoes and hurricanes.
Consider adding more space if you want to store supplies in the shelter, but remember that you’ll have to pay more for larger structures.
How To Build a Concrete Storm Shelter
Retrofitting a concrete storm shelter into an existing garage can be complicated, but well worth the investment. Follow the steps below.
- Remove the existing concrete slab and excavate to the depth you need.
- Construct a wooden form for the shelter’s walls and ceiling.
- Install reinforcing steel throughout the structure.
- Pour small-aggregate concrete so that it fills the entire form.
- Use vibration techniques to eliminate air pockets in the concrete.
- Allow the concrete to cure for 24 hours before you remove the forms.
- Install a certified storm shelter door and electrical components.
Use this method to construct a monolithic concrete structure that weighs approximately 30 tons. It will protect you from even the most severe weather events. For more ideas on how to build a structure, check out FEMA’s booklet Taking Shelter from the Storm: Building a Safe Room for your Home or Small Business (FEMA P-320).
Foundation Considerations
Make sure you have a proper foundation before you build any storm shelter. If you’re retrofitting, be certain the shelter’s foundation is separate from the home’s foundation. If you’re building a new home, you can integrate the shelter’s foundation into the home’s design.
Reinforcement and Materials
A shelter can only withstand extreme weather if you properly reinforce it. Make sure your structure contains the following elements:
- Concrete walls and roofing that are between 6 and 8 inches thick
- Extensive steel reinforcement
- Specially designed and tested doors and hardware
- Ventilation systems that maintain air supply
Ventilation may be the last thing on your mind during the construction period, but it’s very important in the event you need to use the shelter.
Outdoor Storm Shelter Options
If you don’t want to modify your home’s interior, consider an above-ground or underground outdoor storm shelter.
Above-Ground Shelters
Above-ground shelters offer several advantages:
- Can double as storage space when you’re not using it
- Little risk of flooding or trapped water
- Offer easy access for those with mobility issues
- Simpler installation process
These structures are typically made of reinforced concrete or welded steel, and attach to a concrete slab
Underground Shelters
Underground or partially buried shelters protect homeowners by using the earth’s natural shielding properties. Consider the variables below when deciding whether this model is right for you:
- Can be challenging to access quickly
- May require a pump system to remove water
- More complex installation process
- Potential for flooding in high water table areas
Make sure that you build your structure within 150 feet of your home’s entrance for quick access during emergencies, no matter which model you choose.
Meeting Building Standards and Regulations for Storm Shelters
Your storm shelter must meet the building standards below so that it correctly works when disaster strikes.
- FEMA P-320 guidelines for residential safe rooms
- ICC 500 (International Code Council Standard for Storm Shelters)
- Local building codes and zoning regulations
These standards cover aspects such as structural design, door and hardware requirements, and ventilation specifications. Always work with a licensed engineer or certified storm shelter manufacturer to make sure you comply with codes. If you’re having trouble deciding on what type of materials to use, consult The National Storm Shelter Association for a list of products that carry a seal of approval for debris impact resistance.
