I recently roughed in house for a friend. The carpenter refuses to vent straight out of the roof, not wanting to put holes in the roof. That attitude doesn't seem very professional to me. There are two vent terminals, since it is a big rambling house with fixtures at both ends, and the owner added fixtures after part of the DWV system was built. The carpenter ran one vent through the wall while I was away for the summer, with two 90s so it points to the ground. I've explained reasons for the need for a vertical exit, free flow of sewer gasses, frost considerations (Alaska), difficulty in case of clog, potential to become an animal nest, etc. but another plumber friend of his says the gasses should exit OK. Do you agree? I'm looking for more points to convince these guys this is a stupid way to go. Also, the carpenter removed the vent I ran from the bathtub, and capped it off inside the wall. That area of vent with the lav and another toilet and lav above, was built to drain into the tub drain, and now he has created a trap in the wall, and has the homeowner convinced there is no need for a vent off the upstairs tub. He also wants to run the vent on that side of the house out the side and bend it down. I need to convince the owner this is BS. I guess I'm mostly "venting" here, but I am looking for some good arguing points, or thoughts about why the carpenter's methods may be acceptable.