I started with the drain for wash bowl to make it flat with the outside and inside, when I had finished that I glued the top of the holding tank in place with some temporary screws in the corner. In the afternoon I made some foam triangles to put them around the fill pipe for the holding tank so it can be taped with carbon to. Fetske did cut all the necessary pieces carbon to tape the tank and the entrance. When that was ready we put some putty in the corners and tape over it. As a final job we did the floor on the back where the entrance is. This was specified and we taped directly with the same carbon the vertical panel from the kitchen to the floor.