A question on how to get the proper slope in a drain. Let's say you have two section of drain line that must be plumb to each other. To connect these lines by code a 1/4" down slope is needed per foot. The two section are 8' apart so they need to have a 2" slope end to end. Fittings are made with the ports square to each other. The port on a 90 degrees elbow is 90 degrees apart. To me, that means the pipe has to exit or enter the fitting at 0 degrees difference to each other. But, because of the slope there is no way the the connecting pipe can enter or exit the port square and bottom out. They don't make 95 or 100 degree fittings?
PVC fittings and pipes have some play and flexibility to them, especially before the joint has been glued. You simply give the pipe a little muscle and clamp it to the proper slope.