On Mon, 26 Dec 2016 23:05:38 -0000, "James Wilkinson Sword"
wrote:

What is the point of the concrete where there isn't a wall on it? You don't need it in the middle of the house.


They build a lot of slab on grade houses here.
Even when they are on a stem wall, they generally fill the box and
pour a slab. It may be termites. If they get loose in a wood floor you
might end up dropping into the crawlspace.