Subpar Subfloor

During my recent shower size dilemma I was fortunate enough to have one of the John Bridge Forum moderators, CX, catch another major problem with my bathroom renovation. He noticed I had installed the plywood subfloor with the sheets parallel to the joists, thus not making my subfloor strong enough to support a tile floor.

I had used my own twisted logic at the time, and managed to convince Bob, my father-in-law of the same. We thought we were saving on plywood and supporting the plywood edges better to prevent flexing. Turns out this was at the expense of maximizing the ply grain strength and we did not end up with the minimum 5/8ths plywood subfloor strength needed for a tile installation...even though we used 3/4" plywood.

Following the advice of said moderator I used Titebond II to glue additional 1/2" plywood sheets on top of my 3/4" plywood, laying the 1/2" sheets perpendicular to the joists.