Construct30
New Member
In a one floor house and then a two floor house, according to IPC code, is it correct to split the main drain a four inch PVC, say to two different parts of the house using two 3" lines, Then run multiple line through the roof as long as they have the same or more combined area of the 4" pvc. OR do you have to keep one of the lines four inch all the way through the roof. I've done both and passed inspection, but most books show keeping a main line through the house with a main stack vent the same as the main line. Any ideas on what is correct and why?