Richard visits Stephen Davidson of Littleton, Massachusetts to find the source of a strange "fog horn" sound coming from his plumbing system. Then Richard, Tom, Roger and Kevin ask, "What Is It?" Back in the loft, Tom shows the three basic cuts neces... (more)sary to install crown molding. And tile contractor Joe Ferrante helps homeowner Brandon Ingersoll of Cambridge, Massachusetts replace some hard-to-find broken bathroom tiles.