This sounds like the posting for the attic loft. Iím not really sure how your contractor could get away with building a floor using 2x6ís, especially 22" o/c. Thatís far too weak.
However, 2x12ís may be more than you need. 2x10's, 16" o/c should be fine, but your municipality will be able to tell you what they will allow when you get your permit.
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