My sister has a 1960's home and all the bathrooms were recently remodeled before she moved in with all new fixtures and new tile. The strangest thing is that the down stairs bathroom which is only used by guest smells like urine. Not the typical sewer smell but pee. No little boys or dogs use this bathroom. One guest said the smell reminded him of mold. We can not figure where this smell is coming from. It is a pier and beam home with a crawl space underneath and there is another bathroom directly above this bathroom on the 2nd floor. Would a small leak behind the wall create this smell?