Fixing a floor that sags and dips pour self leveling underlayment in the problem area.
How to level an uneven bathroom floor.
A thorough cleaning is also necessary to get the subflooring ready to accept the liquid bonding agent.
Use screws to secure the leveling strips to the floor every 16 inches.
Hammer a shim gently between the floor and the toilet base to bring a low side up.
If you wanna try it let us know and we can help you.
If the uneven floor is due to floor joists that have warped or twisted over time or were incorrectly installed the only way to level the floor is to remove the subflooring and shim the joists.
Compound can correct sags and dips as deep as 1 1 2 inches.
In this video we show you everything you need to know how to level a floor into a perfect flat and level floor in your bathroom using self leveling floor com.
If you have access to the basement or crawlspace it is possible to jack up saggy joists until they are level and then sister them so that they remain straight after the jacks are removed.
Continue to check the level in several directions around the toilet bowl and add more shims as necessary to level.
Screw the strips into the floor joists or subfloor.
Fill cracks in concrete subfloor and make sure the filled areas are level before cleaning the subfloor.
If the floor slants irregularly cut strips that bridge the cap at each floor joist.
I would make the strips narrower than 6 if the floor s slope is not consistent maybe as narrow as 2 otherwise 6 is ok and you will need a 3 4 t g plywood subfloor.
Otherwise your method has merit.
What you really need is to re do the floor the way it was.