Trying to get some stair stringers made and in the process need to figure out our finished flooring details.  I’m wanting to install tile, as this is a mudroom as well as a finished basement.  My question lies in the tile installation and whether or not our current floor will allow for tile given any deflection, vapor or anything I’m probably not thinking of.

So just finished the floor and this is the detail from bottom up

 -Concrete Slab

-6 mil poly / overlapped seams / taped with 3M all weather flashing

-1” RMAX R-Matte Plus-3 Foil faced poly ISO / Foil faced up / Seams taped with foil tape or 3M all weather flashing / 20 PSI rating

-1/2” 4 Ply Plywood / 1/8” gap at seams / ¾” gap at walls / Floating / Set perpendicular to ISO

-1/2” 4 Ply Plywood / Set perpendicular to previous layer / Glued and screwed to 1^st layer with subfloor adhesive and 1-1/4” construction screws / gaped same as 1^st layer

So, I’m hoping to then install an uncoupling memebrain and then tile.  This is my 1^st experience using tile and just want to be sure the floor shouldn’t deflect too much.  When I currently walk around it feels softer than the slab, but still quite sturdy.  However, I’ve noticed with my laser set up, it does bounce a bit when waling by.  Maybe this in normal, maybe not.

Any thoughts?

Thanks!