The top is 6″ thick. Extremely strong concrete mix with a minimum of 6500 psi yield strength. Our units contain over 500 feet of 1/2″ steel rebar welded at every joint to ensure maximum load bearing capability.
Only 2 1/2″ to 4″ thick walls. General purpose concrete mix. Carry as little as 2500 psi yield strength and have little to no steel rebar or wire mesh. Little or no warranty for cracks, leaks, or floating.
Here is a picture that demonstrates the strength of our shelters. This machine weighs 20,000 pounds and is setting directly on our vents!!!