Sorry if it is a nooblet question as I really am. I just picked up the style selections stick vinyl tile 12x12 inc size from local hardware store. THe online guide and paper guide inside the packet mismatch, however it calls for underlayment or primer before installation and after that just start laying the tile one after another. However I am wondering is there a need for any grout? Because I am concerned of the water seal between the tiles? Could it be possible to get a water between vinyl tiles if no grout applied? Thanks