Preventing Gaps in a Linear Shower Drain Installation - ACO's compression coupling
You have two things going on. You need a two piece clamping drain with your ACO linear drain (plain edge model). You have decided to use Hydro Ban (directed to
Dedalus and his other post) as the waterproofing so this needs to tie into the clamping drain. This happens between the lower and upper pieces. The Hydro Ban gets sandwiched between the two.
Now how you do this is key.
I used a little NobleSeal TS on this shower build. The Hydro Ban was only back up to a NobleSeal TS bonded shower ban liner.
After a three week flood test (got kicked out of the job by the drywallers) I came back to install a simple liner drain over top. That is another leading drain shown in the picture and one we stopped using ages ago because of a few hygiene issues... Another reason to stop was the gaps between the drain and the collar. You can see large gaps there.
To prevent mortar from dropping into the drain line ACO has made a little compression gasket for their drain. Have a look...
This gasket (grey in color) comes with the White (PVC) or Black (Cast Iron) versions of the two piece clamping drain.