Found stain on living room ceiling directly below master bath. Ran water from all fixtures but could not recreate leak. Opened ceiling in living room to expose piping and found shower drain to be plumbed incorrectly. Shower had no trap, it was undersized, and pipe was not glued into strainer. Cut out section of joist because shower drain was centered directly over joist and I could not fit a trap. Made a box using 2â€x10â€s to keep structural integrity. Ran new drain line from bottom of shower strainer and added a trap and increased size of pipe to meet code. Ran water for several minutes after completion and there are no leaks. Cleaned all garbage up and everything is in working order at this time. Customer must have Sheetrock repaired.