How to Build a Homemade Storm Shelter in 11 Steps

You can choose between building an above-ground or below-ground shelter. Above-ground shelters are usually less expensive to install compared to below-ground shelters. This is because you don’t need to rent excavation equipment. The cost to excavate land includes the rental of a backhoe tractor, which costs around $100 per hour or $2,200 per week. The larger the project, the higher the cost of the equipment; a large storm shelter project may increase these expenses by up to 50%. 

It’s often better to hire a local excavation company, as you could save money and time in the long run. You can avoid hefty costs and still DIY your storm shelter by opting for an above-ground shelter, which doesn’t require excavation equipment.

Above-Ground Storm Shelters

Pros:

• Accessibility: Easier to access, especially for people with mobility challenges or disabilities.

• Natural light and ventilation: Above-ground shelters can have storm windows and vents for natural light and airflow.

• Cost-effective: Generally less expensive to construct compared to below-ground shelters.

• Versatility: Can be installed indoors or outdoors and can serve other purposes when not in use.

Cons:

• Space requirements: May occupy valuable space on the property or within a building.

• Less protection: Typically offer less protection against powerful tornadoes or high winds.

• Aesthetics: Above-ground shelters may not blend well with the surrounding environment.

Below-Ground Storm Shelters

Pros:

• Higher protection: Generally provide better protection against severe storms and powerful tornadoes.

• Space efficiency: Don't consume above-ground space, leaving the property unaffected.

• Long-lasting: Durable construction can provide a reliable long-term solution for storm protection.

Cons:

• Cost: Often more expensive to construct, especially if additional excavation is required.

• Accessibility: May be difficult for people with mobility challenges or disabilities to access.

• Limited ventilation and light: Below-ground shelters may require artificial lighting and ventilation.

Site-Built vs. Prefabricated Safe Rooms

Some companies sell prefabricated storm shelters that make building a shelter easy and affordable. This may be the best type of storm shelter for your property if you already have the space for your shelter’s foundation. 

Site-built shelters are an alternative option to a prefabricated safe room. A site-built shelter refers to a storm shelter or safe room that is constructed on the property or site where it will be used. Unlike prefabricated or pre-made shelters that are manufactured off-site and then delivered to the location, a site-built shelter is constructed from scratch at the intended location.

The advantage of a site-built shelter is that it can be customized to fit specific sizes and design requirements, making it a flexible option for property owners. However, constructing a site-built shelter may require professional expertise and compliance with local building codes and regulations to ensure it meets safety standards and provides adequate protection during storms.

Where you choose to install a storm shelter impacts how your installation project plays out. If you opt for an in-ground installation, keep your shelter within 150 feet of your home to make it easier to access when bad weather strikes. Ideally, consider building an in-ground storm shelter inside your home for added accessibility. For above-ground shelters, you’ll find space may be limited, but you can also avoid excavation fees. 

This is one of the most important steps in a DIY storm shelter project. You’ll want to call a local soil tester to come to your site and inspect the ground. There are several reasons why a ground analysis is a smart move. A ground analysis:

• Lets you know if the water table on your property is suitable for in-ground storm shelters

• Determines if you have a solid bedrock or boulders on-site that could be challenging to excavate 

• Highlights ways that your soil might change during freezing temperatures that could impact your structure’s walls

According to the FEMA criteria for tornado shelters, you’ll want at least 5 square feet per standing person, 10 square feet per wheelchair user, and 30 square feet for bed-bound occupants. 

Hurricane safe rooms have different requirements of 20 square feet per occupant and 40 square feet for those relocated to a bed or stretcher. Be sure to also factor in whether or not you want upgrades like a bathroom, lighting, multiple entry points, and more. 

Your wall and foundation slab thickness play a role in the design of your shelter, too. Check with a structural engineer near you to ensure the installation will be in accordance with the American Concrete Institute’s (ACI) Building Code Requirements for Structural Concrete.

Make sure that your storm shelter meets all permitting and administrative requirements for the location site and type of structure. It’s a good idea to refer to FEMA for resources and criteria information as you build. You can also check with your local code official if you’re unsure of which permits you need to build your storm shelter. Don’t forget to submit your design to the local building office and include the correct building permit fees. Here are some permits that you might need:

• Construction verification for safe rooms

• Building permits

• Electrical permits ($50 to $500)

Most rental equipment charges by the hour, so you don’t want to rent your equipment only to spend time and money cleaning out a room. Clear out the room if you’re using an above-ground space for your shelter. Clean the walls, floor, and other spaces that will come in contact with the shelter. Make sure there isn’t any carpet on top of the foundation for your site, as you’ll need to secure the structure to the concrete foundation. 

If you’re building an outdoor storm shelter, you’ll also want to remove any outdoor obstacles and excavate your site. Make sure you excavate with enough room to accommodate the walls of your structure—which should be at least five inches thick—and the space you’ll need as you build and work around the structure.

There’s no cookie-cutter, one-size-fits-all rubric for storm shelters. If you’re using wood, use a circular saw (and safety gear like a helmet, goggles, ear plugs, and long-sleeved clothes) to cut the boards to the sizes in your design plan, or ask a worker at your local hardware store. If you’re using poured concrete, ensure you have the correct amount. Steel may be hard to cut at home, so your best option is to order steel beams and materials through a supplier. 

Once you’ve prepared both the legal and physical aspects of your project, it’s time to take out your hard hat and get to work. Depending on the material and shelter type, you’ll want to drill your materials into the concrete foundation using a hammer drill. Use anchor bolts and nuts to secure the wooden boards into the concrete and tighten all of the bolts using a wrench for extra security. Build the frame by attaching studs to the pieces and secure the frame using concrete nails, wood screws, and hurricane ties.

Prefabricated storm shelters typically don’t need any construction, so you might be able to skip this section. These shelters are usually made from concrete and can be installed either above or below ground.

Install the steel walls by drilling steel sheets into the studs, being sure to avoid installing materials where your storm door will go. Install concrete walls using a concrete pump. The materials for building a storm shelter are heavy, so consider asking friends to help you in the building process. You’ll need a wheelbarrow or transporting slabs to transport heavy materials to your equipment site and extra hands to construct the framework for your shelter.

For above-ground shelters, bolt the storm shelter to the foundation of your home with post-installed anchors to prevent it from moving. Note that the concrete slab must be up to code for holding your structure, which depends on the weight of the structure. You’ll need to drill directly into the concrete foundation, clean the hole, apply epoxy, and insert the anchor. Since this is an important step, the ICC 500 requires an inspection following the installation process.

Installing a storm door might not add the most curb appeal, but it’s definitely up there in terms of safety. You’ll need an ICC 500-certified door, doorframe, and hinges to ensure your storm shelter door can withstand the impact of wind, debris, and pressure changes during a storm. Make sure to install your door to open inwards so that you’re not trapped inside if debris blocks the doorway. Additionally, you should have at least three heavy-duty door hinges on your door for added protection.