Voila.
Engineered wood. LVL (Laminated Veneer Lumber). Pressure treated wood and traditional lumber.
links: SolidStart, iLevel & Wikipedia.
links: SolidStart, iLevel & Wikipedia.
On the left, SIPs is put in to form the exterior walls by the stair way.
On the right, a close up of LVL on top of pressure treated wood, sandwiching some sort of foam membrane and the concrete.
And there it is.