What size of pipe do you need to use to vent radon?

As I live in Europe I refer to the situation here : there is no specified vent pipe size. All that is required is that there is an airflow underneath the house. We use special holed plates that are placed on top of a missing brick in the wall (here in Europe most houses are constructed from brick, not from wood). What is important is that at both sides of the house such plates are mounted, to guarantee airflow underneath the house.
Keep in mind that the quantity of radon gas is normally minimal, and therefore only becomes dangerous when it can accumulate.

I assume that the situation in the US or Canada is not much different, except that the construction may be different.

Hope this helps. If you require more information , just ask further here, and I'll do my best to get more data for you !

Success!

:)

In NJ a 3" pipe is required.

Heidi, are you installing your own radon abatement system?