i have a house in baltimore maryland and in some spot in the floor it feels soft and dips when anyone walks in those areas.there is about 3' of space between the dirt and the joist in the crawl space which i crawled under to see if the joist were good and they seem to be. i think the plywood is bad? my question is what type of subfloor should i put down? cdx plywood? press board? or is there a new type of under layment on the market? i have scene plywood that has bin treated on one side but are in small peaces 2'x4'. i want to do this replacement one time and get a life time of use out of it. after the sub floor i want to put down wood flooring like it is now.
thanks for any suggestion