I have just purchased new on the market, Roma Stone vinyl peel & stick floor tile 18 X 18 for my kitchen. Currently I have old peel & stick tiles which will be lifted up to put down the new tiles. The current floor under the tile is 3/4 inch plywood. My question is: Should I use an additional adhesive product in addition to the peel & stick backing to secure the new floor or am I guilding the lily in this case. I also intend to grout between the tiles as an added strength & look as the product manufacturer recomends.The manufacturer sells the grout specifically for the product.