user-1137156 | Posted in Building Code Questions on
Can a Radon vent be tied, legally, into a plumbing vent or must it remain separate through the roof?
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Short answer: No
Slightly longer answer: Pressurizing or depressurizing a plumbing vent with a fan can defeat the P-traps on the drain plumbing. The drain traps are only keeping out the gases by the liquid in the trap. Fans powerful enough to depressurize a basement slab can often drive 2-4 water-inches, sometimes more, and interfere with the operation of the drain traps.
Dana is right. You can't use a plumbing vent stack for a radon mitigation system. For more information, see this article: All About Radon.
Martin & Dana,
When I asked the question I was thinking only of a passive system which I'll be installing as a precaution. If it turns out that a fan must be added it certainly must be separate but if passive is sufficient fewer holes in the roof is desirable. In the article "All About Radon" Martin specify s PVC pipe for the Radon vent. Is there any reason that ABS pipe should not be used for this purpose?
Whether the system is active or passive, you still need to keep the riser for the radon mitigation system separate from your drain-waste-vent (DWV) plumbing system.
You can use either PVC or ABS for your radon riser. Even copper would work, but copper is expensive.