This past summer, a few of us were playing darts down in my unfinished basement. We noticed a rotten animal smell that became very strong and remained the rest of the day. The next morning, I set out to find the smell, but it was completely gone. Weeks went by and then it returned in the same location. Again, could not find an animal, then the smell quickly dispersed. Lately we have also noticed this same smell in the playroom directly above the area where the dartboard is. It will last a few hours, and then go away.
My experience with smells from dead animals is that they linger continuouisly until the animal is completely decomposed, or disposed of. This smell comes and goes for going on a few months. My brother-in-law, a property inspector, suspects its an insulation smell. I have exposed insulation along the top edges of the basement and he suggests that I seal it off. I am not sure if that will work or keep the smell from the playroom. Any ideas?