soil vent pipe

[jimtwo]

I was wondering on a 1100 sq. ft house bath and 1/2, the main septic line that comes in the basement is 4"pvc then goes up and not yet threw the roof, still under construction, but can this 4" pvc be reduced to 3" to go threw the roof? 4" coming out the roof will look to big we think, thanks

 

[Matt30]

It wouldn't pass code here in Canada. Not sure where you're at.