I am remodeling a basement that has elevated levels of radon. I was looking for suggestions for the best/simplest product for sealing off radon penetrations.
Thank you,
Rsquared
I am remodeling a basement that has elevated levels of radon. I was looking for suggestions for the best/simplest product for sealing off radon penetrations.
Thank you,
Rsquared
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Replies
call a professional on this one.
Wait a minute?
Your own house?
Your own liability?
Hmmm...Your own families health?
yeah, call a pro
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
You can't seal Radon out completely because the interior of the house has lower pressure than the earth surrounding the basement. The gas will enter any and all cracks and seams and since it's so heavy, it will accumulate in the basement level.
It's better to install a vaccum system that pulls air from below the slab and exhausts it outside. These systems cost anywehere from $500 to $1500.
Had this discussion before on other forii.
It's true, the ambient pressure in the house is lower than the gas pressure below, and that's why I espouse the idea of slight (very slight) positive pressure in the house. A 12v muffin fan would do to trick. This isn't at all related to the military idea of sealing out poison gas. This gas comes in at very low pressure, in very small amounts and is not poisonous in the way miltary poison gasses are, and if a small, positive ambient can be maintained for even half of the time, it would mean far less infiltration.
The standard, accepted technology seems to be a patchwork of things that don't do what is desired, and that is to keep the Radon out, not vent it.
I'm sure my idea will recieve the usual firestorm of criticism from some, but it IS a direct approach to a simple problem.
Regards,
Don
The radiochemistry lab where I worked maintained positive pressure, and sub-slab ventilation, and was made from concrete trucked in from several states away (local concrete contained too much Uranium and Thorium) all to eliminate radiation sources so lab detection limits could be really low (lower background radiation=greater sensitivity). If a house is really tight, positive pressure could be maintained at least part of the time (the lab had air locks at all entrances to preserve positive pressure all the time). Not a bad idea for an ultra tight house, don't think it would work in a leaky house. Typical tight house air exchangers would also reduce Radon.
Quite right!
Even a slight pressure cannot be maintained or even achieved in an old, leaky house. Moreover, Radon infiltration isn't much of a threat in a well ventilated house, such as the case where there is no sheathing, housewrap, etc.
I live in an ancient, timberframed building which can hold no pressure even though we've been 'tightening' it up for many years. The drapes no longer sway when the wind blows, but trying to pressurize the house would be ludicrous.
It's newer, airtight houses that pose the greatest problem. The conditions are ripe for retention of many gasses that can be even more damaging than Radon. Every kind of building material outgasses after the house is built, even wood. Clean, well dried wood probably causes the least trouble, but it does release moisture and some chemistry. Drapes, carpets, plywood, paint and most other materials produce a load of pollutants, and if they aren't removed, can cause serious health issues.
The upshot of these points is this: Those airtight houses ideally should have a positive pressure, however slight and should have an efficient air-to-air ventillation system as well. Certainly, commonly available technology doesn't provide those conditions. That's why some new thinking is needed in the HVAC industry.
Best regards,
Don
Don,I like your positive pressure idea for homes that have a complete exchange of atmosphere only once or twice a day, and the leaky homes that have a complete exchange once or twice an hour, as you said, probably don't have much to worry about (though a few poorly sealed, old homes between Reading, PA and Morristown, NJ have still registered from 100's to 1000's of pCi/L--rare cases, these).The houses between these extremes are too loose for a positive pressure gradient, but tight enough to potentially build up radon and the other gasses you mentioned. Then, the use of foundation sealing and passive venting or power venting is the prescription. By the way, the common basement sealer, DRYLOK, claims to reduce Radon infiltration.I have two almost divergent lines of thought on Radon, as you have probably noticed. A keen interest in details of remediation and a reluctance to employ costly measures if not really necessary.My former boss at the Analytical Lab certainly advocated remediation for high levels of Radon, however, he was of the opinion that the EPA had set the threshold too low and felt that their credibility may suffer if future studies don't justify the 4 pCi/L action level. He suggested that the level was set to garner funding for EPA programs, the lower the level is set the greater the number of concerned citizens with Radon above that level. The 4pCi limit means that 25 to 30 million taxpayers have an interest in funding EPA work on remediation. Meanwhile, some studies paradoxically suggest that Radon slightly above ambient may actually reduce lung cancer and in Cornwall, England, Radon 100x's the average level has produced no corresponding increase in cancer, actually no increase in cancer at all. That my boss disagreed with the EPA was an understatement. I found this interesting because most of the labs work was provided by the government and often our testing was for EPA compliance of one kind or another. He felt strongly enough about this topic that he was willing to bite the hand that was feeding him. Man of principle or fool? Time will tell.
>> ... paradoxically suggest that Radon slightly above ambient may actually reduce lung cancer ...
Nothing paradoxical about it. Many harmful agents, including radiation and many chemical elements and compounds we usually think of as poisonous, are actually beneficial at very low doses. This effect is so common it even has a name, hormesis. It describes the well established and well documented fact that for most kinds of cancer causing radiation, the graph of number of tumors over radiation dose look likes figure (c) in the picture below.
The last time I was reading about radon, some years ago, my sources indicated that there is no epidemiological evidence correlating increased residential radon exposure to increased lung cancer risk. The radon dosage in most American homes is on the horizontal part of the plot in figure (a), where it is causing no harm, or on the part of the curve below the dashed line in figure(c), where it is actually helping rather than hurting. (BTW, ignore the numbers on these plots. The shape of the graphs is what's important.)
The EPA recommendation is simply bogus science. If they think figure (a) is the right theory, they have no basis for concluding the 4 pCi is the correct threshold. If they think figure (b) is the right theory (and there is evidence that many radiation activists do think so) then 4 pCi is even less defensible. It's just how low they think they can push it politically, with no regard at all to the science.
View Image
The picture is from
here , which contains a link to
here , which references an article by two toxicologists, Edward Calabrese and Linda Baldwin, in the February 13, 2003 issue of Nature magazine (p. 691).
Nice graphs and links and stuff.I definitely needed a little help in here, I haven't been doing much reading on this lately. My posts had no documentation, but I wasn't trying to write a research paper here either. Just get some dialog going.Though I really appreciate your post, I don't think I would live in that Boyertown, PA home that had 2,500 pCi/L of Radon. However, I should restate that it does appear, from my reading, that most damage from Radon is in conjuction with smoking or second hand smoke. I don't smoke, but if I did and couldn't quit and lived in a Radon hot spot...I would put in a mitigation system.One more note, in support of sub-slab ventilation: these systems can obviously be a waste of money (some homeowners insist on wasting money),
however, they can also help keep basements dry (lessen mold/mildew and reduce damage to foundation walls and slab in expansive (bentonite) soils. I guess that is beside the point, just more to think about.Thank you
>> However, I should restate that it does appear, from my reading, that most damage from Radon
>> is in conjuction with smoking or second hand smoke.That's true of other cancer risks, as well. Most of the asbestos damage seems to have happened to smokers.>> I don't smoke, but if I did and couldn't quit and lived in a Radon hot spot ... I would put in a mitigation system.Can't argue with that. If you have two risks that reinforce each other and can't mitigate one of them, it probably makes sense to mitigate the other one.Sufficiently high doses of radon will certainly cause cancer in some poeple. I can well believe that uranium miners have more lung cancer than molybdenum miners, for instance. I'm just not convinced that the radon levels found in most homes pose any risk to people who aren't already overstressing their lungs with some other harmful agent.
Just had another idea, a guy could just smoke outside and save on the Radon mitigation (only about 0.1 pCi/L of Radon outdoors).Now you've gone and mentioned asbestos, this thread may morph from Radon mitigation into Asbestos abatement.
I commend your former boss for his great courage. Few are willing to go the extra mile for principle.
I believe that some of the houses that are somewhat less than airtight but not as open as very old houses could benefit from a positive pressure system by utilizing a larger fan. Any pressure, even a very slight one will do the trick and is worth trying before spending thousands for a technology that may provide little more result.
By the way, the HVAC industry would display courage if it developed an air-to-air heat exchanger that takes up less room in the house, is relatively passive and doesn't corrode into uselessness in a few years, as we see in some built with thin steel members. They would make less profit on each unit, but the public would see the benefit of deploying one in their homes. I think an approach of using convection as part of the process and thin, plastic membranes as transfer media would give good results.
Regards,
Don
One of the best bosses I ever worked for!Knew his stuff, and never flinched when he knew he was right.You might make your first millions in HVAC.
Edited 2/23/2005 11:05 pm ET by basswood
"By the way, the common basement sealer, DRYLOK, claims to reduce Radon infiltration."
Not drylok, but Sanitred makes a bold claim about massive reducitons.
http://www.sanitred.com/Radon.htm
Have you encountered this product? I'd estimate an application thickness of over 2mm. It's just like painting a swimming pool liner on the basement surfaces.
(I used their product to seal a 1/2" crack in my block basement. I'll vouch for the waterproofing. It works for that.)
I might try Sanitred in my basement, could use some waterproofing down there, thanks for the tip.DRYLOK is making that "Reduces Radon" claim now in bold letters on their can, though I'm sure there are better products like Sanitred.
What TJK said.
I'm thankful for the loyal opposition! It's hard to learn much from those who simply agree with you.
How elevated?
The EPA set the level for remediation at 4 pCi (picocurries)/ Liter.
Every home has some Radon, average is about 1 pCi/L. This amounts to a dose of about 100 millirems of radiation/yr and is about 1/3 of the natural background radiation dose the average American recieves (oddly enough, we get more radiation from the Earth than from the Sun).
What do you plan to do with your basement?
Radon levels drop roughly in half each time you take the stairs up to the next level of your home (Radon has a very short half-life and decays in a few days reducing the concentration). If your Radon level is, for example 8 pCi/L, in your basement where the reading was most likely taken it will be at 4 pCi/L on the ground floor and 2 pCi/L upstairs (if you have an upstairs). If all your bedrooms (where you spend 1/3 of your life) were on the 2nd story, and your basement was just for storage or occasional use--it may not be significant. If you planned to put bedrooms in your basement the course of action may need to be more involved. If you smoke, the mitigation is also more important (radon daughters--which are more strongly radioactive than radon--evidently latch on to smoke particles and catch a ride into the lungs where they produce some of the harmful effects usually attributed to smoking). Radon levels close to the EPA guideline may be mitigated by simple caulking of cracks and expansion joints and sealing concrete.
You may be able to try the least expensive option first and retest. You may also want to conduct a longer term, more accurate test. Short term tests can be rather inaccurate (if barometric pressure is higher or lower than average during a short test, results will be off). Caulking and sealing will need to be done even if you have to step up to sub-slab ventilation. Often sump pits can be used for sub-slab ventilation systems.
I don' t want to dissuade you from mitigation, just hoped to provide some perspective. Get as much information as you can, and make an informed choice.
More food for thought:You actually receive a larger dose of radiation from your food (organic or not) than from all cosmic sources (solar and otherwise)--largely due to a radioactive potassium isotope that decays into argon gas (changing from a metal to a noble gas inside your body releasing radiation in the process). Cosmic radiation jumped up a bit last month, when a star 50,000 light-years away hiccuped and sent a pulse of gamma rays across the galaxy (more energy released in 1/10th of a second than the sun produces in 100,000 years or something like that--good thing it wasn't close--we'd be fried). I know that is trivia, and a bit off the topic. I am just revealing a bit of a radiation soapbox. Radiation is natural, after all, and even makes life possible (in dozens of different ways, but I digress). Back to Radon. Tens of millions of American homes probably exceed the 4 pCi/L Radon threshold established by the EPA. Many millions of these homes have never been tested, and several million may seriously need some form of remediation.However, it should also be said that the EPA guideline is a recommendation, not a law, largely because the jury is still out on Radon's precise role in lung cancer rates. Geology and relatively airtight construction in Finland have combined to boost that countrys' average Radon level to about 2.5x's the US level, but the occurrence of lung cancer is lower. Genetics may play a role in those stats. In the more heterogeneous mix of people in Cumberland County, Pennsylvania the lung cancer rate is below average even though Radon levels are nine times the US average and more than twice the EPA's "safe" level.Just my thoughts and a few stats.Be well...confused! (sorry about the ellipsis)
Basswood.
My house is literally located in a town that is a Radon "hot spot" 10 pCi/L I believe is the average, one of the highest in WI. I've looked into testing, but never done it. My house is very "loose" 1920's construction, plus it sits high atop a windy hill. So I'm not that concerned but....
It still has always been a concern. Any suggestions for radon testing kits? I do know the long term ones (min 30 days) are the only accurate ones. Just so many on the market, I don't know who to trust and the prices are all over the place.
Jon
Alpha Track Long Term (90 days to 1 year) Radon Test Kits are considered very accurate. Many people buy the 1 week kits usually available at hardware stores, I think this is a mistake (short term can let you know if a long term test is in order, but shouldn't be relied on for deciding about possible mitigation). Anyway, the Alpha Track costs anywhere from $5 to $40, depending on source, quanity and whether analysis is included. $25-30 is ballpark for one detector w/ analysis. It is a good idea to do a long term test for each level of your home if you live in a hot spot or if a short term test is high.Your house sounds like it wouldn't hold on to too much Radon, wouldn't hurt to check. I've also seen people sold mitigation systems with little, if any, benefit. If you do need to mitigate, you can order a fan direct from ramgam.com. Quiet, good bearings, etc. Last one I ordered cost about $350, I think. PVC pipe is cheap, and rubber bushings isolate vibration from your house (skip isolation and expect to hear a constant hum). To be effective, it should draw air from a sump or gravel below the slab, w/ basement, sump cover, etc. sealed. The fan should go in the attic so the system has negative pressure within the conditioned space. I believe the engineer at RAM/GAM would be happy to give you details on proper installation. $1000 - $2000 is where installation prices usually start, might get in trouble with mitigation pro's, but contractors or accomplished DIYer's should be able to handle it (you may not be permitted to do this for hire w/o certification in many states, however). A follow up test with Alpha Track or another long term test will let you know if you succeeded. Again, try sealing everything first & test, if "too hot", then add a passive sub-slab vent & test again, then if still too hot, buy the fan. Some people are sold a $2500 system right after a 4.0 pCi/L result from a one week test, when a few tubes of caulk and concrete sealer would do fine, for less than $100.
I believe around here to reduce radon in the basement, they run a PVC pipe from the basement, straight up and out the roof.
If that doesn't bring the levels down, they put a blower on it.
But that isn't sealing it off... just blowing it along.
jt8
The reason so many people never get anywhere in life is because when opportunity knocks, they are out in the backyard looking for four-leaf clovers. -- Walter Percy Chrysler
Power venting the slab may not be necessary. Depends upon the severity of the problem.
Folks have talked about maintaining positive pressure within the structure, but that is not generally practical, particularly in the basement, and would waste a lot of energy in most cases. May even cause (or worsen) moisture problems or ice dams.
Normal weatherization practices that reduce exfiltration at the top of the structure will reduce (radon laden) infiltration at the bottom of the structure. Does not create positive pressure, but does reduce the extent of the negative pressure.
Combined with sealing obvious cracks in and around the slab, and/or laying down a membrane (like Tu Tuf) below the finished floor, these measures could be enough to reduce your level to an acceptable range.
So you save energy, increase comfort, and create a healthier home all at once. Good deal.