Installing vent through roof close to an existing vent, any restrictions?

[Mike Rock]

RE-doing my bathroom and want to install a new vent through the roof about 2-4 feet away from an existing roof vent.

Any restrictions on how close plumbing vents can be ? It is well away from any windows or roof ventilation caps.

 

[Terry]

The vents are expelling sewer gas. It's fine.
The only restrictions are air intakes and windows.

 

[Sponsor]

 

[hj]

IF it is that close why can't you combine them?

 

[Mike Rock]

IF it is that close why can't you combine them?

The original vent is cast iron and not really accessible, its inside a wall. It would be a pain to try and combine it.
It would be a lot easier for me to run a new PVC one in a more accessible part of the attic.