Undermount Tub Deck . This design also allows you to build a surrounding deck that aethetically matches your bathroom in a very intentional way. I am a new old user to softplan. Modernized Master in Naperville Undermount tub with matching cherry from www.pinterest.com I'm having an undermount 30 x 60 tub installed and was told i couldn't use tile because it can't be sealed properly where the tub meets the tile. Looking at a kohler underscore tub in an undermount location (back side of tub against a wall, but not an alcove). I am doing a small bathroom remodel and need to show a under mount tub and deck.