Armstrong swift-loc flooring system??????/damp floor
You could seal the tiles by applying a waterproof sealant between tiles during installation or by applying a seperate layer of polyurethane after you install it.
Ceramic tile, not Armstrong or Pergo, is the most ideal for damp locations because it will resist water/dampness. (Be sure to seal the grout.)
As for the dehumidifier, you can also install a vent fan to ventilate the room and make it the same humidity as the rest of the house. It is a good idea, and it is "Code" for all new bathrooms in most communities. A dehumidifier is also a good idea for basements for health reasons, as well. (Fewer allergens and molds grow in a dry basement, and basement air is often the source for furnace/air conditioner systems).
Finally, the tarpaper idea is for a mositure barrier. It is commonly used, but often is overkill. Odor can occur, but usually the tarpaper is covered enough by something to prevent the smell from seeping.
[This message has been edited by Lawrence (edited March 28, 2001).]