All tiled showers will have a waste for water to go to the drain.
The shower will use either a central drain or a channel drain, which is positioned at the lowest point of the shower for the water to drain to and then be discharged into the plumbing drainpipes.
Each shower, whether a central drain or channel drain, has a Leak Control Flange (LCF) and this flange is the connection point.
What Does It Connect To?
The flange connects to three items:
- The substrate/surface of a bonded element to prevent movement.
- The plumbing pipe that will discharge the water.
- The membrane.
The above three items are critical to the LCF working as it has been designed to do.
The Importance of LCF Height
Another very important item is the height at which the LCF has been installed.
Why do we say this? Because the height will determine the fall rate of the shower and also how the LCF can be detailed when the membrane is applied.
The detailing of the LCF is clearly illustrated, in principle, from the IWAM Code of Practice.
The detail shows the membrane being applied from the surface with fall onto the LCF surface.
The same type of detail is provided in the standard AS3740-2021.
This detail clearly shows the:
“Horizontal adhesion dimension of flange”
This note is critical to achieving correct membrane detailing, as most membranes require an apron to bridge from the surface of the shower to the surface of the LCF.
If the LCF is too low or covered by screed/base, then the apron cannot be used.
When the LCF Is Covered
TANZ sees some manufacturers of tile-over bases or application of screed covering the LCF, resulting in the inability for the membrane apron to be used or allowing for the “Horizontal adhesion dimension of flange” to be membraned to.
This issue has resulted in showers leaking at this important junction.
If the flange is covered by either the base or screed, then it is not possible for the membrane to be detailed onto the flange.
Grate Support Pipe
In addition to the importance of the LCF is the use of the grate support pipe, which is to be cut to the correct height.
This pipe is to sit on the spigots, which then allows a gap for sub-tile moisture to drain.
If the pipe is not used, then debris from the water attaches to the tile adhesive and creates an unhygienic environment.
Also, if the grate is not supported by the pipe, then the grate is sometimes supported by tile adhesive, which often blocks any area where sub-tile moisture can drain, which affects the performance of the shower.
Correct LCF Installation
The LCF should always finish flush with the surface of the shower floor area that will be membraned, so that the membrane can be applied from the surface of the floor to the surface of the flange.
In addition, the waste grate should always be supported by the waste adjustment pipe and be placed on the waste spigots so that sub-tile moisture can drain to the waste.
TANZ Recommendation
TANZ always recommends following the information found in the TANZ Best Practice Guide: Tiling and Wet Area Construction, as this publication has a proven successful history and is the only tile guide endorsed by MBIE. 😊