Home Improvement Questions? Ask a Handyman for Answers
You don't need and probably shouldn't use tar paper under a carpet. Maybe the previous owners were worried about pet urine soaking into the wood sub floor. But tar paper is never used under a carpet.
I'm logging off for the night. If you have more questions I'll respond in the morning. If not I'd appreciate a favorable rating
If you have an exposed dirt crawl space then the vapor barrier should be in the crawl space not under the carpet. You should put poly on the ground. You can also attach it to the bottom of the floor joists.