I bought a 1962 house with pink tiles everywhere. I removed them. Under that I found a 3/4 plywood sheet covered in thinset mortar. I ripped that out. Under that I found the badly damaged original hardwood flooring and some areas with plywood (kitchen,etc).
My plan is to put a 1/4 thin plywood subfloor over this original flooring and then put in engineered wood flooring.
The issue i have is that there is many spots where the original hardwood is badly damaged or missing a piece.
So my question is what should I use to fill these holes? Latex leveler?
Also is 1/4 plywood too thin considering there will be solid hardwood and plywood under it to provide firmness? I think I want to staple the engineered wood flooring. Will the staple be able to go thru the 1/4 plywood and then penetrate correctly the hardwood under?