Laying the drains and vents for the house took several days. We had hoped to have an inspection after only 3 days of layout and gluing but after 3 days we ended up asking for a courtesy inspection instead of an actual inspection. Our city, Arvada, will provide the courtesy of coming out and checking the installation and providing advice before the actual inspection.
The inspector arrived in the morning and took some time to evaluate our installation plans and make recommendations which we very much appreciated. My research and interpretation of the code had included dry vents for each fixture, but the inspector said that was unnecessary and recommended wet venting instead, so we took his advice and reconfigured the master bath plumbing. It took us several more days to implement all the changes that the inspector recommended but it was time well spent since our objective is to pass inspections so that we can move to the next step.
Notice how there is only one vent for all four bath fixtures? Toilet, sink, shower, and tub all drain into the vented pipe. The 4″ white pipe to the right of the photo is the supply chase and not part of the drain system.
There is one vent on the bathroom drain and one on the laundry drain. The inspector recommended air vents on the floor, utility sink, and the kitchen drains. Air vents cost about $20 each but they avoid having pipe connections in the ceiling across rooms.
The drain exits under the door threshold where the original drain exited. The 3″ pipe on the left is the pipe that crosses the entire house from the shared bath in the existing part of the house and the master bath. That drains into the 4″ pipe on the right that is the main house drain. The inspector said 4″ was required for this main drain but we had already planned 4″ at the proper fall of 1/8 inch per foot. The 3″ and 2″ pipes require 1/4″ per foot of fall.
Originally we had the drain cleanout inside next to the family bath toilet, but the inspector said it should be outside with a smaller cleanout inside at every vent stack.
The inspector also asked that all the pipe be bedded in fine gravel for the inspection and explained that we needed a test tee just inside the exit to the sewer/septic tank for the test ball. So we purchased a truckload of finer gravel and it was spread under all the pipe ensuring the pipe had the correct fall along the run. Also installed the test tee. all these changes took about 4 more days of layout and gluing.