Redoing a bathroom, and the floor is all over the place (three different heights). The subfloor in the main walking area is 3-1/4 inches lower than it needs to be, while one area is 2-1/2 inches lower, etc. (some joists were cut down 1-1/4″ from others in the original framing).
The finished floor height needs to be 3-1/4 higher than it is to match the hallway entry.
As a result, I need to build up one part of the floor by 2-1/2 inches, another by 1″, and the third area by 1-1/4″. (True, precise measurements–plus 3/4″ of mortar/decoupling membrane and mortar.)
Since plywood actual measurements never add up to those dimension, how would you suggest I layer the plywood subfloor to get as close as possible to those buildup heights?
For the 2-1/2″ depth can I just lay a 2×4 across the existing subfloor (in the area that has it!) and layer on top of that? Can I use tar paper as “shims”–or is there a better material to sneak up on those true heights/depths?
Replies
Have you considered taking it all out and starting over?
Maybe down to the joists?
Are they in “plane”?
I’d just make the subfloor stable and strong. Screed it out with deck mud to make up any elevation issues.