1st floor bath. plywood subfloor. sheet vinyl. good shape. but totally glued down. should i put down 1/4" cement board and than tile? or lay tile on top of vinyl floor? i hate to try to tear up vinyl and have it shred. i know it is plywood from viewing below. but it is 1 or 2 layers of wood? won't know till i get toilet up to measure wood thickness. townhouse was built in 1980. bath floor feels solid.