Sanitary tees aren't supposed to be used in a horizontal drain but what about at 45 degrees. I am trying to put in a sink, but I am space limited in running the drain pipe in the wall. This will connect to a horizontal pipe with a wye. If I put a Tee in vertically (vent up, drain down, and middle would be sink connection), then I would need a wye+45 to connect to the horizontal pipe, but there isn't enough vertical space. There is vertical space if I put the tee in at 45 degrees and go straight in the wye. I am assuming that tees are not used horizontally because of problems directing flow. If that is the case, 45 degrees should be sufficient to direct flow downward, at least in theory. Anyone know if there are any issues to consider with that sort of setup?