I bought a new home and the existing deck is some type of vinyl waterproof blue covering over plywood. I would like to install a cedar or composite deck. The current deck is new so I would like to install cedar or composite over the existing deck. Would this be a problem?
No one here can see what your seeing.
Going to need to see what it is you have now, no clue what is it by your decription.
Not likly though, decks need air flow on all sides or there going to mold or rot out.