jodijodi
Cathlete
As Chris said, my floor is not actually touching any of the walls. It is at least an inch away from both the back wall and one of the side walls, and it is between 4-6 inches away from the other side wall (the side with the TV). It feels very solid, and does not shift at all.
The moisture barrier is recommended in the Stagestep instructions, and also by the handyman who helped us install it. I'm not that familiar with the details, but I think the idea is that because the concrete is touching the ground below it, it can "sweat" from the moisture. This would ruin the wood floor above it unless you put down plastic to keep the moisture away from the wood and foam. I think it is a standard part of installing any floor over concrete in a basement.
The moisture barrier is recommended in the Stagestep instructions, and also by the handyman who helped us install it. I'm not that familiar with the details, but I think the idea is that because the concrete is touching the ground below it, it can "sweat" from the moisture. This would ruin the wood floor above it unless you put down plastic to keep the moisture away from the wood and foam. I think it is a standard part of installing any floor over concrete in a basement.