During my dishwasher drain cycle or when I drain water from my kitchen sink, I can hear a pipe in the ceiling(directly above the dishwasher) make a “creaking” sound – similar to the sound wood makes when it expands and contracts. It also sounds like a drip, but the sound is so pronounced that I have a hard time believing it is a pipe leak. This is perplexing because I can’t understand why a pipe in the ceiling is making sounds when the water should be draining down to the basement– not up. I do have a second floor bathroom directly over my kitchen so I’m not sure if this bathroom and my kitchen share a drain pipe; however, when the second floor bathroom (i.e. shower, sink, etc.) is being used, I do not hear any of the sounds from the pipe. I have checked the ceiling drywall for wetness, but all seems to be dry. Can anyone shed any light on this issue? TIA for your help.

The drain pipe is getting hot and expanding form the dishwasher drain and the place where the pipe is rubbing against the wood is at the ceiling level. Actually, its probably the vent pipe that is moving. If the lower half grows, the upper half must move.

Yep, Harold is correct. Your kitchen vent pipe is doing its job, venting. The cold air from outside gets pulled into the vent as the water drains down. This air is, at least in Illiois today, 75 degrees colder than the pipe so it contracts. No real fix at present unless you are willing to open the ceiling, are you?