Installing a 48x32 shower base and have cut the 2" pipe just below flush of the drain. My pan is just not quite level. Rocks just enough to drive me crazy. Was told to use morter to adhere it to the concrete but I feel I need to level it first with something that pours like water and hardens to the concrete. Doesn't need a lot plus I can't build it up for two reasons, I had to chip the concrete around the 2" drain pipe about 1 1/2" down and around so the the drain on the pan slips over the pipe and this is also why I have to have a thin layer of something to level the concrete before putting the pan down. The floor is higher just a bit right at the drain. When I lay a 2x4 down it rocks just a bit. I'm afraid it I just use the morter the will be rocking soon after. I but down 4 2x4's in the middel of the basement floor and put two pieces of plywood down spread out enough for the pan to sit down and the drain hole to slip through and not touching the floor and the pan is level as can be no rocking what so ever. Any help as to what I can use for a thin layer to even out before sitting the pan down would be greatly appreciated.