Adapting to an existing 2-stage drain with KDAR
There are a number of reasons why you may want to consider using the KERDI-Drain Adapter, or KDAR (KERDI Drain Adapter Ring). (1) You want the assurance that the plumbing connection was completed by a licensed and insured plumber - peace of mind. (2) You have a shower remodel and would like to work with the existing drain connection. No problem.
A two stage drain will be secured over the surface of the subfloor (concrete or wood). Concrete box outs may allow the drain to be nestled just below the height of the rest of the floor as you may be able to custom float to the height you want.
Wood, on the other hand, is set. When using a Schluter TT (Thin Tray) you will need to lift the height of the tray to offset the height of the drain body and drain adapter. This can be done with compensation boards such as 1/2” tile backers, scrap floor rated OSB, drywall or KERDI-board (easiest to work with). I recommend KERDI-Board or cement backer when lifting trays over concrete.
Use the KDAR stainless steel ring with orange rubber flange gasket and the drain body to determine which bolt pattern to punch out. Use a pen or screwdriver to push the orange gasket free from the bolt holes on the drain adapter that match the bolt holes on the drain body.
Use a liberal amount of the KERDI-Fix that comes with the KERDI-Drain Adapter kit to (1) encircle each individual bolt hole, and (2) join those circles with a solid liberal bead of KERDI-Fix as shown in RED in the photo below. Discard the clamping ring that came with the drain body. We only need the bolts. Press the KDAR into the KERDI-Fix and use the bolts from the clamping ring to fasten our KDAR to the drain body. Do not over torque. Suggested to hand tighten first and then use a wrench to secure 1/4 to 1/2 a turn.
Use plenty of thinset underneath the flange to ensure proper support. Any excess mortar that bleeds through the trapezoid shapes of the flange should be spread over the last remaining recess in the tray with a KERDI trowel to complete the KERDI donut connection from the drain flange and the shower tray.
