I know this topic has probably been discussed here on the boards before but I wanted to run my plan by someone before I move ahead. I've decided to tile my basement slab. Sounds to me like installing ditra as an underpayment would be the best option. However, the basement does get some moisture, particularly at the edge of the room that faces the backyard. My question is this: if there is a little bit of moisture that comes in, would I run the risk of trapping some of that moister under the Ditra? Would I be better served by skipping the Ditra and tiling directly over the slab? Thanks in advance!