I’ve removed carpet and other flooring from my living room, dining room, and kitchen. My main question relates to the living room. I’ve attached a marked up layout of the room illustrating the subfloor (non)flatness. The subfloor is 1/2” particle board on top of 5/8” plywood, with joists running north/south and resting on an east/west beam down the center of the house.
In order to get an accurate picture across the 24’ x 27’ L-shaped area, I shot a laser line from wall to wall set at the same height on both walls, and then I measured the floor’s deviation every foot along the beam. Those are the green lines on the picture.
My biggest concern is area #1 in the living room. When shooting east/west across the joists, I get a trough that’s up to 5/8” deep in the center and runs left/right across the room. I think I could bridge the area with a 12’ screed, but that seems like an awful lot of material. Is that the right approach?
Shooting north/south across the areas (along the joists), there’s minor deviation, but it’s flat enough to deal with the small spots easily, I think. I’m not showing the dining room & kitchen results on the layout.
The red areas represent humps in the subfloor, but it looks like those should sand down relatively easily.
Does what I’ve described make sense? If so, do you have any particular suggestions for handling it apart from lots of thinset?