When a building is going to be built eight feet above ground level, its foundation is different from the foundations that many of us are accustomed to seeing...or at least those of us who are drawn to look at foundations.
For most stateside construction, whether the building is block or wood, a trench is dug - a trench that follows the entire outline of the building to be constructed (few buildings or foundations are constructed these days of brick...faced with brick, yes; built with brick no). Concrete is poured into this trench; concrete that's reinforced with rebar. This is the footing - this is what the building sits on.
Block and/or wooden structural components are then attached, or "tied," to the footing directly or to a foundation, depending on the building material. Tying all these things together is supposed to keep the building (the top part) from sliding off the footing (the bottom part). However, recent events have shown us that nature can quickly undo what we do, despite our best efforts - and despite our compliance with extensive building codes.
But an all-around-the-outline footing doesn't work when a building sits off the ground on stilts: there's no outline.
Instead there are a number of smaller, discrete footings, each of which is concrete that's reinforced with rebar. In much of the United States, footings are dug so as to be below the freeze line - a depth that increases as one travels farther north. At False Bluff, Cesper has put the footings really deep - obviously not because of freezing but in order for the resultant building to better withstand high winds or storm surge. And also because the first level of 'soil' below the surface at False Bluff is sand: the individual footings for these two cabins are in solid soil.
Concrete, reinforced with rebar, was poured into the deep holes and allowed to cure. Tied into, and rising up from, each of these footings is a concrete post; and then tied into each concrete post is a wooden post. The cabin framing will be attached to the wooden posts starting eight feet above ground level.
Eight feet is a fairly common ceiling height in lots of new stateside residential construction. At False Bluff eight feet is the height of the outdoor "room" beneath each cabin The cabin's floor-framing itself ends up being the ceiling of the outdoor space.
Cesper's video does a nice job of showing all this, and of Hebert at work front and center. If the sight of the black wooden posts waiting to be set is confusing, see the November 21, 2017 post about treating wood against termites.