All shelters meet or exceed FEMA 320, 361, and ICC-500 standards. They have been tested at Texas Tech Wind Science & Engineering Research Center. Steel rebar used inside the walls along with fiber mesh for structural integrity. All 6,000 psi concrete (weighing about 12,000 lbs for a 6×8 model).
Manufacturer’s warranty guarantees there will be no leaking for 10 years from the date of installation.