I am remodeling a 100+ year old kitchen...all is going well and my last activity is the flooring. The majority of the kitchen is over a basement, the remaining third is what used to be a side porch that was reclaimed as a dining area and enclosed with studs and sheet rock. I know that the part over the basement has the same original wood flooring that is in the rest of the first floor but I can not see under the other part as it is essentially behind a wall/foundation in my basement. My assumption is that it is not the same and likely porch wood, running in the same different direction of the flooring in the house but probably a different type or in poor condition or that it was torn out. If I thought I had a chance I would consider pulling everything off and trying to refinish the old floors but I am assuming that given some of the short cut "improvements" that were made in the house this might not be the case.

Anyway all of it is covered by old plywood. On top of that is the all too typical "brick" vinyl that is so old that it is dryed out and cracking in some areas...would take a chunk out of a barefoot if you were foolish enough to walk on it's cracked edges. I am taking that out and want to put in new sheet vinyl or maybe vinyl tiles. My question is can I use the existing plywood subfloor. It is not in the best of shape in the areas where it has been exposed due to the old vinyl failing and breaking up but...let me tell you how well nailed down it is...someone went nuts nailing this down. Can I just use a leveling compound where it's a little torn up or do I need to remove the old plywood, assuming that I have to remove all the old vinyl. From what I can see we are only talking about very limited areas, isolated to door openings (2) and in front of where the frig used to be (probably due to a leaking dishwasher).

thanks for any responses