They are joined with 7/16 dowels. Two per leg. The wood movement should be compatible, but the grain is so wild on the top, it is a bit of an open question. They are glued into the top sockets, but dry socketed, loosely into the legs. Near the top inside of the legs there are small wood thread "set screws" that go into the dowels to lock them into place. Thus the piece can be disassembled by loosening out the set screws and pulling off the legs. And, pulling out the cross brace tusk tenons of course.
Dowels are not the strongest way of making the joint, and I debated doing a wedged through tenon, but I decided I would like the disassemblability and the use case does not demand maximum strength anyway. I sit on it to put my shoes on in the morning. And the occasional shirt might get tossed on there. Not rigorous use. Also, I have hopes that if the wood movement is not well matched the dowels can wiggle a bit in their dry sockets and perhaps, if need be, break, sacrificially, before the top does. But I really hope the wood movement is properly matched and I won't ever have to rework the piece.
I did lay the cork floor myself. It is quite easy to do, and those are not the snap together sheets, just ~3/16" thick rectangles of cork. The hard part is finding a water based adhesive. (Although, where you are tk, you've probably got access to much more than I). And it is a lovely floor material. Warm, soft, easy to install, inexpensive. Basically the perfect floor for a bedroom.
Gropius put cork flooring in his house in Lincoln, not far from here. And I used to see it at the old Fogg Art Museum where there were cork tiles in the non-public areas since probably the 1930's or before that had developed the most alluring "patina" (for lack of a better description). I kinda fell for the look and feel under foot there, I guess. The old Fogg has been wholly transformed recently by Renzo Piano, BTW. Into what, exactly, I'm still not sure.
But, hey. How about Leif's cool bench?
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