I am considering a crawl space foundation for a new addition. The main reason I would like to go with the crawl space foundation is due to costs. One option I have is to install a concrete floor or not install one. Just wondering the pros and cons of the concrete floor. What are the moisture, radon and mold levels without the concrete floor? What does everyone recommend? The options I guess would be to install the concrete floor or leave it dirt and cover with a 6mil vapor barrier and insulation. Any info would be appreciated. Thanks.