We will be gutting a bathromm soon because of a leaking shower.We have had carpenter ants coming out from the walls and want to make sure we solve the problems correctly. What do you recommend as underayment to the ceramic tile which will be installed.Our contractor has suggested Dens Shield or Durorock. A tile installer has suggested Wonderboard. We plan to have an exterminator come when they rip out the walls. Please help us!