I had to replace some rotted walls in my bathroom and ended up replacing portions of the floor as well. Since we were at this point we decide the old peach colored tub had to go. When I put down the new 1/4" underlayment and vinyl sheet do I run this underneath the tub or just up to the skirt? The new tub is fiberglass, or Vikrell I think is the tradename. Anyway the new tub has numerous "pegs" for support on the bottom were the old tub had just 8 and I didn't know how or if this would affect what the tub sat on.