Replacing Wood Sill with Limestone.

DJD

Hi there, I've removed my 5ft patio door, and eventually will replace it with a vinyl sliding door.
I've removed an old PT door sill. It was tared over brick to attach it to the house. I am pretty sure that was installed wrong.

I've removed the old tar before the picture was taken.
I want to add a limestone door sill, which is pictured. The brick is above the ledger.





Now my question is how do I add the stone in? I was going to add some mortar between the brick and stone, but how to i attach it to the wood joists?

I was planing on shimming the stone on the wood joists to have proper drainage slope, but how would you attach the stone to the wood? I would put blue skin over the wood before the stone also. The stone will have a about 2" of overhang.


Also when the limestone is in, do I need to put a vapour barrier around the stone?

Thanks.