Getting ready to install 3/8" x5" wide engineered on top of 3/4" plywood sub-floor. (will glue down as per manuf instructions) I want to know how I should go about getting the hardened glue (from former hardwood install) up from the sub-floor in order to prep it for the new stuff. Not a whole lot of high trowel ridges present. Can I put chemicals on the glue or is that a no-no because it's on plywood?

If I can use a chemical to soften it, which brand would be recommended?

BTW, I'll be trying to remove this glue from approx. 1450 sq ft.

Finally, the old engineered I pulled up had been laid parallel to joists on this 3/4" plywood sub-floor. The floor was approx. 16 yrs old and I did not notice any defects from it being laid parallel and the squeaks were only in a few places throughout the house. Can I lay the new stuff parallel as well without adding anything to the 3/4" sub-floor? If you recommend I build it up, what size do I use?

Thanks from Arkansas

I wouldn't use chemicals. Besides other factors, your running the risk of the chemical affecting the new adhesive. Depending on the adhesive, it can be sanded off.

It's no problem to install a 3/8" engineered parallel to the joists. Ofcoarse if you felt like you wanted to sheet it out....that takes care of the existing adhesive problem.