Our model was designed for above-ground installation. Our shelter is constructed of galvanized steel, and the thickness varies. The small size is 4' X 6' and the large size is 8' X 10'. Either, depends on the type of installation. With either anchor bolts or expansion anchors.
Expansion anchors come with the unit.
The unit was designed so that the customer can do it himself, or have someone else install it. Sole requirment is to have and adequate slab for unit. We have a generic design that can be use anywere in the US other than swamps. However this has been discussed with TTU in depth. Their opinion is that none is required as a search and rescue team will get you out within 4 hrs.