I need some help. I have removed a particleboard overlayment to the subfloor due to previous owner's pet stains (extensive). I have two areas in the subfloor where the joist is not completely flat and it has a realtively high spot in the floor. The result is a 6'x8' area that needs to be leveled out. I'd like to flatten the subfloor before I install the 3/4" T&G OSB Sturd-i-floor. Should I use the self leveling products where you mix up a batch, pour on the floor and then the product levels itself?

My floor will look like this when finished...

3/4" Solid Hardwoods (Stapled)
15# Asphalt roofing felt (stapled)
3/4" T&G OSB Sturd-i-floor (screwed into joists with 3" screws)
(in spots the self leveler)
1/2" OSB Subfloor (nailed to joists)
2x10 Floor Joists

Does this make sense? Will it work?

Bump - No one can answer my question?

Nevermind, I found out that the product I want to use is cementuous and would breakup and crackle over time.

Otherwise, the floor is reasonably flat in most areas. Would using the shingle method help in this case (to "ease" the transition up to the high spot)?

Any help is appreciated.

Easier to sand down a high spot than fill in all the places lower than it. If it's a high joist, remove the subflooring just where the joist is high. Plane down the joist and replace (put back) the subflooring. Now it's flat and ready for your underlayment.

I use an edger to sand out smaller ridges in the sub-floor. For larger areas I opt for the planer. use this attached to a shop vac. If you need to take off 1/8" or more in a larger area this is a great way to go.

If you use this in combination with a pack of asphalt shingles under your Sturdi-Floor you will be golden.

Also the 15# asphalt roofing paper will leave a noticeable telegraphed line if you overlap it accordingly and the light is right, and your product is a pre-finished floor.

A better vapor barrier would be aquabar or fortifiber.