im looking to install a tile floor in my basement. theres alot of glue residue left over from the carpeting that was once there so it would be easier i think to make a subfloor and put the tile on top of that. ive read some other threads and a subfloor over conrete seems to be frowned upon. my basement is extremely dry, there has never been water down there from the outside since weve moved in 3 years ago. would i be ok with just plywood over the concrete since my basement is so dry? also whats the best way to attach the subfloor to the concrete? thanks

A friend just purchased an older house with a dirt basement floor and brick foundation. The house is located in an area with known wet ground. It is heated via a warm air furnace located in the basement. Due to the high levels of humidity in the basement, it is not used to store anything (else it would grow mold). The problem is that there is a lot of moisture accumulating on the windows (relatively new, thermalpane double glazed) inside the house. I suggested that he lay plastic on the dirt in the basement, but mold started growing under it within a few days, so he removed it. Eventually, he would like to concrete over the floor, but that is likely several months or years off for the time being. Is there anything he can do now to help reduce the humidity coming from the basement and up into the house?