I stripped my kitchen floor down to the diagonal 1x6 slat sub floor (1940s). Did as much research as i could and found 1/2" plywood screwed to the diagonal floor every 3 inches on the border and 6 inches in the field would stiffen the floor up. I also screwed the diagonal planks back down i to the joists (16" o.c.) with 2" wood screws. Now that i have that down, before i put down cement board or whatever backer i decide, im wondering how LEVEL do i need the floor vs how FLAT. My floor sags roughly 1/2" in 10' across the room. Should i seal the edges of the room and pour self leveling concrete? Can i even do that since i have a hundres screws in each piece of ply? I obviously want to do as good of a job as i can, but i keep finding conflicting opinions on self leveler. Some say just fill dips and sand down peaks, others say level the entire floor.Any opinions will be greatly appreciated. Thanks. via /r/DIY http://bit.ly/2vhz194
