Sill plate over cinder block posts question?

[Vassili07]

Hi, I was just hoping for a little clarification. I'm building a 16'(runs parallel with house) x 8' addition on my house. I'm going to be adding three piers to support the new addition spacing them 8' feet apart. The piers are going to be  cement blocks on a 2'x2'x12" footer.

My question is I see many examples of putting a 2x4 sill plate on a cement wall foundation, but nothing about putting sill plate over piers. Would I be ok bolting a 4x6 on my three piers as a sill plate, and then running my 2x8 floor joists/ header joist on top of that (the other end of the floor joist will be tied right into house using hangers)?  Am I over doing it with the 4x6 sill plate?

This image best describes what i'm planing on doing.

[Don_P]

A 4x6 would work as a block cap, or a 2x8 and cap the whole block. The bolt(s) should be tied to rebar that extends though the solid poured pier and hooks to the footing rebar. If you're asking if a 4x6 is enough to act as a girder on an 8' span carrying floor and roof, no. Your snow load is the unknown at this point in sizing a girder.