I am installing a floating engineered wood floor in our master bedroom. There is one step up at the doorway into the master bedroom which means I will have to use a stair nose molding at that door opening. My question is: Can I use a flush stair nose? I am concerned about affectecting the ability of the floating system to expand if I have to nail the flush stair nose down? If I can't do that should I try to use some type of overlapping stair nose molding instead?

Laminate floors are always floated, so there stairnoses have an "over the top" milled into it. Because engineered stairnoses don't have that, and you must maintain a floating floor, I have seen a "T" molding used. I think it looks like a trip hazard, myself. Call the flooring manufacturer, and have them fax you exactly how they wish for you to handle it, and maintain a warranty.

most floating floors now have products for stairs , really in the last 3-5 years have they come a long way ,so yes check into it ,but i'm sure you will find something