I have a radon remediation system in my basement. The installer told me the only cracks in the basement floor that needed to be sealed were the ones within 5 feet of the PVC vent coming out of the slab. He explained that all the other minor cracks were actually good for operation of the system because they allowed replacement air to enter under the slab as the remediation system vented out all the radon. He explained that if everything was sealed tight the unit would create a mini vacuum under the slab and would shorten the life of the venting motor.
I have heard recently of installers that seal every little crack and crevice in the floor, with the explanation that the system is useless if radon can “leak†thru floor cracks. The only exit should be the vent.
Does anyone have an opinion on what is the right approach, seal cracks or not? I have searched the net looking for official remediation solutions to see if these issue is addressed but I haven’t had any luck.
Thanks for your opinions.
Ryan
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You could try this on the building science forum at JLConline too.
I think that technically, it should eb all sealed, but his theory sounds good.
Wanna know how to be sure?
close the house up for a day with the fan running, and then do another radon test in the basement. Compare findings to what you had before it was installed.
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While the theory sounds acceptable, and testing might show that it works fine, the thing to keep in mind is that the goal is not to make the fan last another thirty years or so. The goal is to help you last another thirty years or so. The fan motor can be replaced.
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Thanks Piffin for your suggestions. The tests are cheap enough so I’ll have another one done and see if there has been a change in the radon level.
Ryan
Money well spent. it will either give you a sense of whether he is full of it, or put your mind at ease, both laudable investments.
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If you have a known radon problem, you might consider one of these:http://testproducts.com/safecart/product_info.php/cPath/26/products_id/70/?source=Overture&OVRAW=radon%20alarm&OVKEY=radon%20alarm&OVMTC=standardI've seen them on the web as low as $70, and you get the first result in 48 hours and updates every 4 hours after that. We did a long-term (9 months!) canister test last year and the lab results were 5.1 pC/m^3. We installed a radon alarm in the same area and the readout showed 5 pC/m^3 -- pretty good accuracy. As for the cracks, I'd go ahead and fill them. The purge system will have a better vacuum under the slab if there are fewer holes in it.
What results did they get on the re-test after the system was installed?
Also, at least in theory, a radon mitigation system can create draft problems with your combstion appliances (furnace/boiler, water heater) by increasing the negative pressure in the basement.
I haven't seen that happen in the houses I've checked, but I can't rule it out.
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Edited 1/12/2005 5:26 pm ET by Bob Walker
ahh.... a subject near and dear to my heart. I just sold a house that had a very slight radon problem- it tested out as a "5, while the EPA states that it should be under 4. Anyway, not wanting to lose the offer, I had one installed for $800. Basically all they did was core a hole in my basement slab, dig out a little dirt, insert a length of 4" PVC, and rout it out the side of the house and up to the inline fan. All the sealing they did was at the juncture of the slab and pipe and since it was in the corner of my basement, sealed the juncture between the wall and slab foot feet in either direction.
At first I was concerned about the pull of the fan because we have hard clay soils in my part of the country and was worried that it wouldn't draw the gas from beneath the slab. Boy, was I wrong. As part of the installation and purchase offer, he re-tested and it dropped from a "5" to a ".2" and my slab is cracked like anyone else's!
So, get it re-tested and if it is not working, he needs to come back. My guy told me a story about a 38 year old woman that died of lung cancer, she was a non-smoker as well but her house tested out at 50! They attributed the cancer to radon.