If you read much on this site you’ll know that I use the Kerdi waterproofing system to make sure the water in your shower goes down the drain.  Part of this system is the Kerdi drain.  The problem is that sometimes I’m asked to tile a shower where the client has already had a plumber install a standard clamping drain.  I believe that the conventional pan liner/clamping drain method of collecting the water in a shower is problematic (or perhaps doomed- the way this drain was mounted above the subfloor is a perfect example of one issue I have with these things.  Read more about that here.) So, what to do?


1.  Cut it out-  Most of the time it’s easiest to just cut the clamping drain out and proceed as usual.  It mostly depends on how much access I have to the pipes.

2. Use the Kerdi Drain Adapter-  For this project, north of Spencer, IN, the clamping drain was already there and I had no access from below.  I can cut the drain out from above, but for this one I thought I’d try the Kerdi Adapter.  I’m pleased to report it works well and was easy to install.  Here’s the process:


The first step is to remove the top of the clamping drain, saving the bolts.

Then the adapter ring is bolted down over a ring of KerdiFix (or a 100% silicone caulk), then the flange is set down through the orange gasket into supported mortar.

For this project I was using the 48″ x 48″ Kerdi shower tray to form the sloped floor.  The only issue that I had is that this needed to be raised up about 1/2″ to be flush with the flange after it was installed.  To do this I installed a layer of 1/2″ cementboard over the level subfloor and then installed the Kerdi tray over that.  If the clamping drain had been recessed it would have all worked perfectly.  Of course, you can building your own sloped base as well.

The flange on the adapter kit extends several inches into the drain so that the silicone and gasket are mainly there in case things overflow.  I was very happy with the drain adapter and won’t hesitate to use it again if the situation arises.