DIY Radon Mitigation Help

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Fireguy5674

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My old house has a large, open crawlspace besides a small basement. I am going to do a radon test to determine if I have excess radon in those areas. Even if I do not find high radon levels I would like to seal the open dirt off from the house. What is the best way to seal the floor area of crawlspace? This house was built in stages. Some of the crawlspace would be from early 1900's and the rest plus the basement is from 1940's. The foundation is mostly soft brick with the basement walls being old cinder block. Bricks are laid on the ground with no foundation and depth varies with outdoor topography. If I find excess levels of Radon is there any good way to mitigate crawlspace area without installing suction system? Looking for ideas. Oh, the other catch is I am going to have to move dirt to level the space and/or remove dirt to be able to reach some areas of the wall. Just not as svelte as I used to be.
 
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Never had to deal with radon. The crawl spaces we do have 6 mill poly wrapped up the wall a little like 2" glued there with acoustical sealer If the poly has joins they should over lap at least 12 inches
or taped with red TUCK tape. Around the walls Tape around any plumbing that come up from the ground. Then it gets a 2" skim coat of concrete. If you also put in concrete you add sill gasket anoud the walls glued with acoustical sealer it get a good seal.
Do your radon test and then figure that out.
 
I did a Radon test after I did my encapsulation have no idea what it was before or if the encapsulation even had much affect on it.
But our Radon level was literally like fresh outdoor air.

this is a copy/paste of our radon test.


12/10/14 ACTIVATED CHARCOAL RADON TEST #6749232

* Radon Test Result = < 0.3 pCi/L

* Test Started 12/02/14 at 4:00 pm
* Test Ended 12/08/14 at 10:00 am

* Location 1st Floor bedroom


** INTERPRETING YOUR TEST RESULT

The US EPA action level for indoor radon is 4.0 pCi/L. Test results in this range(0.5 pCi/L or less) are, for all practical purposes, equivalent to the radon levels found in fresh air. However, if you make any structural changes or start to use a lower level of the building more frequently you should test again.

Here is another thread that may help you.


http://www.houserepairtalk.com/showthread.php?t=17610&page=2

One thing to note though is that IF our Radon test had sucked and way over 4.0pCi/L then because of totally sealing our crawlspace all I would have needed to do was set up a Radon mitigation pump and suck the air from under the 12 mil plastic to the outside.

It is possible that sealing our crawlspace tightly with 12 Mil on the floor, then sealing every tiny little hole and crack with closed cell fire foam and then adding slight pressure to the crawlspace via a vent from our plenum may have mitigated some Radon, enough to basically give our house the equivalent of fresh outdoor air.
 
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