what does the falling f the house represent in the novel the fall of the house of usher

The family name is Usher hence the name of the place is called "The House of Usher". When Madeline makes her creepy appearance and Roderick is pushed to insanity, the house starts to come crashing down. Thus the fall of Usher is manifested in the physical sense and a family sense. The connection between house and family seems symbiotic. There doesn't appear to be any directly related Ushers left and their house is certainly an insurance write off!