: I have to run a sink drain (1 1/2") through 7 joists. Most of the joists are 9 1/2" TJIs and 2 sets are double 1 3/4" x 9 1/2" LVLs. According to mfg instructions both can permit up to 2" holes (or larger for TJI). What technique do I use to run the rigid pipe? It seems like I have to have a coupling joint between each joist. Is there a simpler way? As far as setting the slope, I imagine I'd just take a level and measure down 1/4" for every foot?

Chad,
Most of the time with plastic pipe, you can bend it through the first hole and using a hammer and piece of wood, bang it through all the holes. It helps to have someone guiding the pipe through the next hole.
If you don't have the second person, you can "pull" the pipe down into the joist hole as needed.