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Thread: Radon Test

  1. #1
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    Default Radon Test

    We don't have a lot of radon activity here, so I've never done a test. I want to do one for my new house since it does have a walk out basement and it is very tight construction. What are the best mail away tests to use?

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    Jim Robinson
    New Mexico, USA

  2. #2
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    Default Re: Radon Test

    I haven't used canister test kits for decades, so I'm not up to speed. However, I'm guessing that just about any home test kit is going to be about the same as far as quality goes.


  3. #3
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    Default Re: Radon Test

    Jim

    hire a certified radon tester and get a good test--it's only $150 at most--a little more then the big box testers--come on man

    cvf


  4. #4
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    Default Re: Radon Test

    Here is another radon test question from another non-radon tester, I think I know the answer (common sense, but is the common sense 'right'?

    We are purchasing a second home in the Asheville, NC area, with a moisture barrier covering the ground in a vented crawlspace (feels like 10 mil). I am planning on overlapping another layer of moisture barrier over the existing layer as the joints are not really overlapped (may have been overlapped years ago), a roll of 10 mil Visqueen plastic sheeting at the Big Box stores looks to be about $200.

    Being as the crawlspace is vented, is there any reason to get a radon test?

    Is there a need to put another layer down, or just tape the seams of the existing layer (which looks pretty good from a quick look at it)? Home inspection is being done next week, I won't be there.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  5. #5
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    Default Re: Radon Test

    Jerry,

    Are you asking about the "moisture barrier" (I refer to it as a "moisture retarder", since I cannot verify the perm rating) regarding its ability to restrict the transmission of moisture or its ability to restrict radon?

    If radon, I can't offer any real advice, since I follow in the footsteps of Sgt. Schultz (I know nothing).

    If moisture, then (at least around here in semi-sunny No. Cal.) most moisture or vapor retarders are 6 mil, loose-laid directlly on the soil (sometimes staked-down so the sheets don't get pulled/gathered when someone is crawling around on it), lapped a couple of inches, and will effectively cover 90%+/- of the soil. The purpose is to allow the existing ventilation to be more effective by retarding the evaporation of water out of the soil rather than keep it 100% dry. Of course, any standing water should be addressed with exterior drainage because having water on top of the plastic is not doing anyone any good.

    There are companies that will lay a heavy (20 mil) barrier and seal it to the foundation and around piers. These also generally require a sump pump system and are expensive. The problem that I have is that these "encapsulation systems" need periodic maintenance. Someone has to service the pump, reseal the membrane to the perimeter foundation walls, as well as check the membrane for rodent holes (there are almost always rodent holes in them after a few years).

    If the current plastic is doing its job, then why add another layer? If you need more than something to retard evaporation, then it might be necessary to go to one of those expensive "encapsulated" systems. On occasion, I do see where one would probably be necessary. But generally, a moisture/vapor retarder is good enough.

    Again, this would be true for No. Cal. I don't know if NC would be a lot different.

    Department of Redundancy Department
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  6. #6
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    Default Re: Radon Test

    Jerry

    Ashville nc is a high risk zone 1 on Radon levels which means levels above EPA levels of 4.0 Picocuries. so testing is recommended--vapor barriers are known to lower Radon levels but should be sealed all around foundation and sump pit sealed--again to be safe have it tested--it is a known cancer killer and we don't want to lose you yet

    cvf


  7. #7
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    Default Re: Radon Test

    Gunnar,

    Yes, moisture barrier is part of the question - it all looked dry inside, and is probably 95% or better covered based on the part I saw (I went about half way in, sloping lot starts out about 4+ ft high in crawlspace and reduces to maybe 2- ft at the far end, there was a drain line I didn't feel like crawling under so I stopped, but looked pretty good to that point).

    So I probably don't need to add another layer? Works for me.

    Charlie,

    Asheville is an area of higher radon, however the crawlspace is vented, wouldn't that reduce buildup of radon?

    Any mitigation system would likely require sealing the crawlspace up, just to be able to negatively pressurize it, or sealing the moisture barrier up and to the crawlspace walls and piers to negatively presduize under the moisture barrier?

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  8. #8
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    Default Re: Radon Test

    Jerry

    Radon is a strange gas--I have seen radon high and low in vented crawl spaces all depends on what the foundation is sitting on. Ask around the neighborhood or look for an installed mitigation system around the block--that will give you a better idea---if there is a lot of granite around--that increases possibility--any how enjoy your new home away from home--i get to ashville sometimes--stay at the Omni resort for golf

    cvf


  9. #9
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    Default Re: Radon Test

    Charlie,

    I could install an exhaust fan with a timer to come on once per day (or less often, every few days?) at one of the vents in the crawlspace to extract air from the crawlspace, which would increase the existing ventilation of the crawlspace with outdoor air.

    Of course, if the house has radon gas coming up from underneath the house, then it would have radon coming up from underground around the yard, replacing the crawlspace air with ... radon laden air from outdoors. But it would prevent 'build up' in the crawlspace.

    We've gone to the Omni a few times while in Asheville, not to stay, but just visit, as we were staying a places we rented for a week or so.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

  10. #10
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    Default Re: Radon Test

    I have had very high readings in homes with crawlspaces. Get it tested.

    A side note about asking neighbors etc. I once tested a home and got a reading that was in the 20's or 30's. A week later I was inspecting a house that was maybe 300 feet from the first house's back door. I told my clients that based on the previous test, I would suggest one for this house. It came back around 2.0.
    I was sure there must have been something wrong with my monitor, so I used a second monitor and tested again. It came back very low as well.

    I was very confused, but then remembered my training and how radon gas makes its way up thru the ground to outside air. Since then, I didn't take what other houses performed into consideration.

    Get a test Jerry.


  11. #11
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    Default Re: Radon Test

    Jerry

    the fan is used a lot here in Colorado and it does work in reducing radon #-and Jack also find that a lot here one house high next door low--i found out once thru testing these two houses when i shut the fan off in the high mitigated house for two weeks the low reading next door got higher--as i said radon gas is strange

    cvf


  12. #12
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    Default Re: Radon Test

    Okay, radon test is needed.

    Thank you.

    Jerry Peck
    Construction/Litigation/Code Consultant - Retired
    www.AskCodeMan.com

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