22' span with 12x12 syp

[barasingha]

I am planning to span 22' with 12x12 beams spaced at 4' oc.  the joists will tusk into 6x12 sills that are continuously supported by a rock wall.  Using a 4400 lb load and no2 syp gives a deflection of 1/2".

Would that be noticeable visually or bouncily?  Also what are the opinions on decking for the 3' span?  Would 3x6 tng be needed?

[Den-Den]

* 1/2" deflection will be visually noticeable
* If you have not sized the decking, how did you decide on the dead load?

[barasingha]

I figured 10-20lbs dead and 40lbs live.  It's a second floor loft, not a garage.  I could probably coax a 1/2" crown into the 12x12 timbers if I need to--for aesthetics.