We are on a job where a concrete overburden will be placed over our waterproof membrane. We’ve installed the Mer-Kote ARC under tile waterproofing system on the plywood and have now placed Schluter Troba (the orange stuff) drain board on top. Since water will pass through the concrete the drain board will allow subsurface water to drain out off the edges. Note on top of the drain board is wire reinforcing for the 2″ concrete bed we’ll place today. Watch for more pics when we post a job profile.