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Has anyone ever tied a radon vent stack into the plumbing vent stack to avoid extra roof penetrations?

DanClere | Posted in Mechanicals on

Assuming our new construction waste pipes are all trapped properly there shouldn’t be a chance of sub-slab gasses getting into the house. We’re on a septic system. We’re not really concerned about radon but installed the sub slab perf. pipe as a precaution and currently have the stack capped off in the attic adjacent the plumbing vent stack.

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  1. kevin_in_denver | | #1

    Is it a conditioned attic?

    If not, then energy-wise, you already have an envelope penetration through the ceiling.

    If you are just worried about having another roof penetration because of the potential roof (water) leak, or the cost, then run it out the eave if you have one.

    The building code in your jurisdiction may address the question, and then you have to do what they say. It's probably not a great idea because the vents usually suck air in to replace the water leaving.

  2. Expert Member

    It's a bad idea.
    If you do have a trap that for any number of reasons malfunctions you have created what is in effect an express highway for radon to enter your house.
    It is not permissible under our code and probably not under yours.
    I don't think limiting roof penetrations is a good basis for making decisions about building systems. Roof penetrations should not leak - no matter how many you have.

  3. GBA Editor
    Martin Holladay | | #3

    Here's a document with helpful tips for installing a radon mitigation system: A Guide for Installing Radon Control Systems in New Homes.

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