In article ,
metspitzer wrote:

I have a bathroom where, due to poor calking, the floor has rotted.
The floor is tile and still looks fine, but when I go in the basement
and look at the floor above the floor is rotted completely thru and I
can see the bottom of the tile. The amount of rot is about 5x5
inches.

What I want to do, for now, is use some filler material and fill in
the rotted wood. Then take a piece of plywood and toenail it into the
floor joists, or use a couple of blocks to screw to the floor joists.


Any recommendations on what to use for filler?

"For now?" When do you plan to fix it correctly? After your leg has gone
through the floor and the broken tile has severed your femoral artery?
(BTW, the "amount of rot" is certainly larger than 5" square.)