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Consider: If the wood bit next to the immovable tile has to expand it has to
push the entire floor instead of the board in the middle having to push just
half the floor. Now your floor may be samll enough that inherent compression
of the wood could accomodate the "push," but why take a chance?

Don't nail wood designed to "float." Don't float wood that's designed to be
nailed. At least that's what I've been told.

Thanks for all the advice. I think leaving room for expansion is the
right way to go. The 2 surfaces might not end up even anyway so I'll
need a transition.