I am building a small 18' x 24' barn using rough sawn hemlock. I have built a conventional deck using KD Douglas Fir for perimeter beam and joists. I've used rough sawn 2x8 hemlock for decking. My posts will have stub tenons to attach to the built up perimeter beam.

Question - Should I sit my posts on top of the 2x8 decking or should I have the posts rest directly on the perimeter beam? 

Thanks,
Mike O'