Originally Posted by wdfifteen (Post 8460185)

I did a remodel where new interior walls were being built and did the two layers of plywood and Hardyboard. More recently I put tile in a bathroom where the doors and walls were already up. The subfloor is 3/4 plywood. I got under the floor and added 2x4s to the sides of the floor joists up against the bottom of the subfloor, effectively making them 4 7/8 wide and the gap between them 11 1/4 inches. I added screws into each 2x every 12 inches down from the top. Ditra had come out by then and I used it under the tile. I figured the test would come when I filled the bathtub. The result is outstanding.

Originally Posted by Scuba Steve (Post 8460529)

Nice. At our place I have the unfortunate luxury of needing to replace every joist I come across as rooms are renovated. I've been putting in double 2x8s and adding piers and beams under the center of the span. Nice and solid - can't feel anyone walking around any more even if they're the type that walk on their heels and boom around like a t-rex.