We have a finished, dry basement in our 1955 house. Twelve years ago, we installed berber carpeting and pad over the existing 9" tile floor. The tile is attached directly to the concrete floor. The tiles were in good condition when we installed the carpet.
Our issue is a persistent smell. It's not damp or musty, more of a chemical, petroleum-type of odor. It is strong enough that it lingers on things that have been in the basement, especially fabrics.
I'm suspecting that is coming from the tiles or their black mastic adhesive. Or, possibly the pad under the carpet?
We would like to do some updating to the basement, but I don't want to to put anything new in place until the source of the smell is identified and controlled.
So...has anyone else experienced this? Any thoughts on what it is and how to address it? Should we seal (and with what?) the floor before putting anything new down? Advice on carpeting, esp. backing for this type of location?
I think you already have and therein lies your problem.
All concrete basement floors can experience moisture. Even when you are certain the concrete is dry there can be moisture. Spreading the tile adhesive and then adding tile will create a seal that won't allow natural evaporation of the moisture. Any fabric (especially carpet) will hang onto odors.
If you were to remove the tile and scrape as much of the adhesive as you can, then the carpet may be able to be cleaned after being reinstalled.