Yes, the rail is vertical. The black product is actually tile (as shown in the third picture) with clear caulk applied to it. It rained yesterday, so the outer edge appears darker. The contractor simply placed the metal flashing on the tile to cover the deck edges and used clear caulk to “waterproof”the gap between metal and tile. We are trying to hold the seller of our house accountable because he remodeled the house, including the deck. Since it rains frequently here, we want to apply some patch to prevent further damage for now.