What can I put between layers of subfloor to flatten out a dip

I have a 12x12 kitchen down to studs. I also tore out the top layer of subfloor(particle board). I have a 1/2” dip running right through the middle of it. I bought self leveling compound but am hesitant. The 1/2” plywood subfloor that I would be pouring it on flexes. Which I assume would crumble the SLC. Could I use roofing felt since I am going over the top with more plywood? Is 1/2” too much for felt paper? Am I right that self leveling compound would be a disaster? Any other ideas?
thanks a lot!

 

Roofing felt and even shingles are used to level up a low spot when installing flooring, hardwood/vinyl/laminate but never to the extent of 1/2"

Yes, self leveling will crumble if the sub floor is not rock solid, personally I would never use on any type of wood floor.

Yea, 1/2" is not sufficient, at the min 3/4" with proper joist spacing but you need to address that and get it level and solid.

What is going in?

 

Vinyl plank is going in. If
i can’t use shingles or paper, what do you suggest?

what if I do the shingle/felt paper mix to get 1/4” +/- and then install the top layer of 1/2” ply, and then see where I’m at?

thanks

 

I agree that the floor needs to be solid. One sheet of 3/4" is often stiffer and better than two layers of 1/2".

But as for shimming you just want something that doesn't compress easily. You can use vinyl flooring, VCT, tub surround plastic, roofing felt, rosin paper. Each has it's own thickness so by mixing and matching you can hit the exact thickness you need. But, 1/2" is a LOT. You can rip down a strip of wood or 1/2" plywood for the thickest and then step down to 3/8" then 1/4" or luan and then to vinyl or roofing felt for where you need less shimming.