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Technical Snapshot: Flexible Collars on Pipes

Technical Snapshot

Issue: Flexible Collars on Pipes

Flexible collars used with stacked pipes on balconies have recently seen a trend for them to be placed lower than acceptable or even set into the slab.  Flexible collars are not a suitable substrate to receive a membrane. All penetrations are required to be secured prior to the membrane being installed. Penetrations require a membrane upturn of 85mm minimum around pipes to be compliant with AS 4654.2. 

With the flexible collar located above the membrane on the pipe. Penetrations must be treated with the highest attention to detail and care, as these are some of the most common causes of water ingress and defects.

AS  4654.2 – 2012 states that all penetrations must be properly secured, or have a cast-in sleeve, or mechanically fixed flanged collar before the waterproofing is installed & “Where the membrane termination is to prevent water entry, the finished height of the membrane above the finished surface level shall be sufficient to prevent water, including wind-driven, flowing over the top of the membrane.”


These penetrations have not been properly secured, and their collars are incorrectly positioned. Refer to pic. 1, 2


  • All pipes to be securely cast through the slab with a riser of 200mm minimum, allowing a minimum membrane upturn of 85mm.

  • The flexible collar to be installed above the membrane upturn.


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