We are planning on finishing our basement in the spring. We own an older home which still has a lot of galvanized pipe. Slowly i am replacing with my supply lines with copper. I am almost done with that and plan to start on the drains. we get a lot of back ups, the current drain pipe in the house appears to be 1 1/2" OD. Part of the problem we keep getting our drains clogged (primarily in the bathroom) is my wife has long hair, and i am sure that due to age there is a lot of gunk built up on the inside of the drains. when i begin to replace them with PVC i am thinking of changing the diameter to a minimum of two but thinking of going 2.5 to 3". My washing machine, upstairs dishwasher and condesent removal pump all drain into my deepsink. I want to tie all of these into the vertical pipe coming down from the kitchen sink. when we redo the kitchen we are also looking at installing a garbage disposal.
I am thinking 3" pipes and clogs no more. is this the right way of thinking?