knocking noise

[Joe Massena]

Hello, we just bought a new manufactured home (wick artcraft) on an acre of land.I know I am under warranty and have called for service, however I am curious. There is a knocking noise under the floor in the master bathroom when the waste water drains from the sinks and tub. Has anybody ever run into something like this before?. anybody have any ideas out there? Thank You

Joe

[Tahlborn]

Could you be hearing the waste pipe expanding from the tempurature difference from the water?

Tim