Soil stack venting

[jimtwo]

I was wondering on a 1100 sq. ft house bath and 1/2, the main septic line comes in the basement is 4"PVC then goes up and not yet through the roof, still under construction, but can this 4" PVC be reduced to 3" to go through the roof? thanks

 

[Terry]

I was wondering on a 1100 sq. ft house bath and 1/2, the main septic line comes in the basement is 4"PVC then goes up and not yet through the roof, still under construction, but can this 4" PVC be reduced to 3" to go through the roof? thanks

I depends on your local codes. In Washington State, a three bath home gets by with a 3" or equal for venting. A four bath gets 4".

 

[Sponsor]

 

[jimtwo]

Do you think reducing down to 3" out the roof would cause any problems? I am not sure on codes, but there isn't any inspection required.

 

[Terry]

We do three inch all the time. It's fine.
Normally two 2" and one 1.5"

The kitchen gets 1.5"
And then each bath may get a 2".