We are installing a new bathroom on the first floor of our house, and want to confirm that we are sizing the drain and vent pipes correctly. We are regulated under UPC 2006.

Starting at the outside wall, I have a toilet on 3" line with 2" vent. About 1' past the toilet a 2" line (5' horizontal run) from a double vanity will join the 3" line. About 6" past that connection a 2" (2' horizontal run) line from a spa tub will join the 3". Finally, about 4' later, a 2" (vented) line from the kitchen (sink with disposer and dishwasher) will join the 3" line. This line eventually increases to 4" when the waste line from the upstairs bathroom joins it.

By my calcs, I'm within the allowable DFU's for the 3" waste line and 2" vent line, and allowable lengths for the fixture arms, but I'd like an expert to confirm for me.

Thanks for a great forum.