My mother's house has had an odor in the basement for the last 2 summers. It is NOT sewer gas - which is everyone's first suggestion. It smells like cat urine, but there is no cat. The odor is not there in the winter - whether the smell is gone or the furnace removes it, I can't say. The smell is worse during/after a rain. We have had the plumber, who cleaned out the sewer pipes, etc, and found nothing else wrong. I had the borough engineer out, who was unable to offer any ideas. It seems to come from one corner of the basement floor, and sometimes the bare concrete is dark, as if water is leeching up from the ground. There is never a puddle. We have already tried the enzyme odor removers - to no avail. We are having the tile floor removed and will have the concrete painted with an epoxy paint, but don't want to do the work if the smell will still be able to get through the paint. Anyone have any ideas? Thanks!