Is it possible to put down plywood on existing deck boards in perpetration for vinyl decking or should the deck boards be removed first then put down plywood? The deck boards are in good shape just wondering about proper structure.
If your talking about some form of composite decking then all the old deck boards have to come off, if this is an outside exposted deck then plywood is never ever used.
If this is 5/4 decking then your going to have to add more floor joist if there not now set at 16" on center. Composite can not span 24" without sagging.