I'm assuming you want a frame all the way around the block. Cut two strips 2.5" x 10", and attach them to opposite sides of the 10" square (blue strips in diagram below). Then cut two strips 2.5" x 14", and attach them to the top and bottom (green strips in the diagram). You will end up with a block 14x14" (13.5 x 13.5" finished).
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