Radon Mitigation Question (Tu Tuff Liner)
I am working on a design of a small (12′ x 16′ — 192 sq ft) workshop with a crawlspace that will most likely need some kind of radon mitigation plan. I definitely understand the details and “strategy” of initially putting in the perforated pipe and riser, then capping it so that a “passive” system is in place. If the picocurie readings are high, then one is in a good situation to finish the system or make it an “active” system with an inline fan. My question is this. Why couldn’t one simply use a Tu Tuff liner under the inner slab AND extend it out underneath the footing so that one could block it all together? I am most likely going to use a heavier vapor liner because my space is so small and I would like to avoid having a 3″ pipe run up through the space.
I have seen a few footing details that show a vapor barrier under the footing but those are mostly mono-slab pours. I was wondering if a crawlspace might allow for such an assembly.
Any thoughts on this are appreciated.
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Replies
John,
You can install a layer of polyethylene under the footings if you want. When it's time to install the Tu-Tuf over your crawl space dirt, you can tape the Tu-Tuf to the polyethylene that you installed under the footings (assuming that you left adequate flaps to tape to).
It's also possible to install a layer of polyethylene between the footings and the stem walls -- and if you do, you can also leave enough protruding polyethylene to tape your Tu-Tuf to. For more on this technique -- including a discussion of its advantages and disadvantages -- see Capillary Breaks Above Footings.
All of this said, I'm not sure that these steps will limit radon entry compared to more conventional methods. They can't hurt, however.