Leveling Uneven Subfloor
Screw down 3/4" plywood or cement board for the deep area &amp; 1/4" for the less deep. Then, use very much less floor leveler for a final fill-in. Make sure you account for the flooring, so the 3/4" might need to be 1/2" &amp; the 1/4" may need to be shortened. Do not use shims &amp; create voids.