the other, but bar type fixtures can allow this and still 'center up' on the sink.) peanut's pal. March 12th, 2010 at 6:30 am. Flat pan box or in the trade we call them pancakes. They are only as thick as the drywall. You do need to screw them to a stud though. They make shallow cut-in ... pump is not working so you can stop using the bathroom ... florescent light in the plumbing ... two more pipes, one for a shower and the other for the sink, and put the toilet over......