How often do I need to use an expansion coupling with a PVC drainage system?
For pipe sizes from 82-160mm, there should be an expansion coupling every 4m . We would suggest one every floor on a vertical stack. For pipe sizes 32-50mm the maximum distance is 2m. However, any change in direction where the maximum distance between fixed points exceeds 1m you should install an expansion coupling.
For a more detailed answer and for further reference please see our Technical Bulletin below on Controlling Thermal Movement in PVC drainage systems