[Am I crazy?]

This is my 4' X 5" small 1/2 bath project. I did the demo in the hope of tiling the floor. I tore out 2 layers of linoleum and then discovered I had 3/8 of rotten plywood over 1/2" plywood sub floor nailed to the joist. When I ran the numbers I saw I needed to lower the floor 3/4 " in order for my tile to come out even with the oak floor in the hall and the toilet flange (cast iron). My calculations were 3/4" plus 1/8" thinset layer plus 1/2" Hardy board plus 1/8" thin set plus 3/8" ceramic tile for a total of 1 7/8 "

I also checked and discovered the floor joist were uneven. So I cut the joist using a level and simply started at the high end with a router cutting 3/4" and they all came out pretty darn level even when checked corner to corner.

So I am ready to lay my high grade 3/4" plywood but have been getting lot of confusing info. Let start with joist. They were 5.5 inches X 1.5 Doug fir but now 3/4 shorter and 16 " on center.

My plan is to sister the joist with 2 X 4 to give added strength. Then use 1.5 deck screws to fasten the plywood to the joist and sisters.

Then use a 1/4 trowel to apply thinset between plywood and 1/2 hardy board using appropriate screws and not screw into the joist, just the plywood.

Am I good so far????

Bob