[rich2468]

Wayne,
Thanks for those two good reasonable possibilities.

A drywall anchor should provide a rivnut-like connection with the floor without having to actually press it in place. The existing tank hold down holes wouldn't have to be increased much in size and I think (but will have to examine) that drywall anchors apply most of the force to the back side of the material (vs the sidewall of the hole).

I'm not sure how a toggle bolt would spread out within the flooring foam core. I'd likely have to increase the size of the current holes. I think, due to needing the "wings" of a toggle bolt to spread out, that a toggle bolt may be my fall-back solution.

Your ideas made me re-examine my idea of possibly using a rivnut. In looking at how rivnuts hold, it appears as though much of the holding power of a rivnut is due to the expanding of the rivnut within the circumference of the hole its placed in; with a only a small amount of lip created to prevent the rivnut from pushing in or pulling out.

Digging into the holding dynamics of rivnuts and wanting the benefits of your two solutions (more holding pressure occurring on the backside of the floor vs. the side wall of the flooring holes) has led me to plusnuts and Jack Nuts. I think that both of those ought to be able to expand within the foam layer of the floor to provide holding pressure on the top layer of the bathroom floor.

Thanks for the suggestions!





that's not a bad idea and could possibly have as much or more holding power as a rivnut.