How to Build Your Own Concrete Storm Shelter - Part 2 - The Walls

When a severe storm that spawns tornadoes passes through an area, the intense winds can damage above-ground structures. Strong enough winds may even level houses and other buildings made of common building materials like wood and drywall. A storm shelter provides a sturdy place to hide out in a major storm. Generally crafted inside the ground for extra protection, storm shelters require a strong material, such as concrete, for resilient walls.

Things You'll Need

• Shovel
• Measuring tape
• Plywood
• Shortening
• Circular saw
• Wood stakes
• Wood nails
• Mallet
• 2-by-4-inch wood boards
• Concrete mix
• Wheelbarrow
• Metal rebar
• Reciprocating saw

Instructions

1. Pour the concrete floor for the storm shelter before installing the storm shelter walls. Use quick-drying concrete or a mixture of Portland cement and sand for the slab.

2. Dig out 4 inches from the edges of the slab that you poured so the opening for the storm shelter has extra space on every side of the slab. Dig a ditch around the cement slab approximately the same depth as the slab, 5 to 6 inches deep.

3. Measure each side of the concrete slab. Cut a piece of plywood for each side of the slab that is the width of that side and 6 inches taller than the storm cellar hole. Attach wood stakes to the plywood every 6 inches so that an 18-inch length of each stake hangs off the bottom of the plywood. Use shortening to grease the side of the plywood that doesn’t have the stakes attached.

4. Place the plywood panels into the opening dug for the storm shelter so the stakes are directly against the plywood slab and the plywood faces the dirt walls. Hammer the stakes into the ground until the bottom of the plywood wall touches the bottom of the trench around the slab.

5. Measure the distance between the two longest walls in the storm shelter. Cut 2-by-4-inch wood boards to this size.

6. Hold one 2-by-4 board between the two longest walls so the board sits directly against one of the shorter plywood walls. Drive two 2-inch nails through the plywood and into the 2-by-4 at each end and along the shorter wall, every 6 inches. Place a 2-by-4 at the other end of the long walls, directly against the shorter wall, attaching it in the same manner.

7. Place 2-by-4 boards every 6 inches between the long walls to create a sturdy form inside the shelter opening. Mix a batch of concrete in a wheelbarrow, according to the manufacturer’s directions, and pour approximately 12 inches of it into the spaces between the wood form and the dirt walls of the storm shelter.

8. Place rebar the same height as the storm shelter pit every 8 inches along the perimeter. Sink the bottom of the rebar into the concrete at the bottom of the pit; stand the rebar straight up and center it as much as possible between the wood wall and the dirt wall. Lower a piece of rebar horizontally into the pit on one side of the vertical rebar you just place on each side of the form.

9. Pour another 12 inches of concrete. Lay another horizontal piece of rebar on the opposite side of the vertical rebar already in place. Continue this procedure to the top of the wall space, pouring 12 inches of concrete and then laying rebar.

10. Leave the wood walls in place in the hole for the amount of time the concrete needs to set up, according to the manufacturer's directions. After the concrete sets up, remove the wood form from the hole by pulling it straight up. If you have problems with removal, use a reciprocating saw to cut the nails that hold the 2-by-4 boards in place at the top of the form.

Tips & Warnings

• Be sure and bolt and brace your forms real good because of the pressure from the concrete.

• Any all thread rod that sticks out after you tear down the forms can be cut off if not used for bolting seats and shelves.

• Wear gloves and eye protection when working with the concrete forms.

References

• Fema: Concrete Wall Plan
• LS1M: How to Build a Storm Shelter
• The Family Handyman: How to Build a Storm Shelter
• University of Missouri: Concrete Basement Construction