In front of the water heater there was a large hole cut in floor to run vent pipe and pipe to grey water tank. also another large hole that was cut in the wrong place for the vent pipe. When I turn on the fantastic fan in the bathroom it draws air out of the area underneath the trailer and you smell the mold smell. A can of foam will stop the smell problem by closing off the 2 large openings. But I told the dealer I would like to find out where the mold smell is coming from under the trailer. When I find out I will post. Sometimes the manufacturer uses moldy wood in the subfloor and that might be ok if the floors are sealed properly and the smell cant get into trailer. The trailers are assembled by people and some do good work and others don't. Quality control is a big problem with most manufactures.