Hello All!
Have a 1924 story and a half cape, 800 square foot basement with a slush coat floor. The finish is pretty rough, tons of cracks in the floor and around the perimeter. The basement floor is about 4 feet below grade with a 6 foot ceiling. We spend a lot of time down there, especially in the summer. It also has a radon level of 9.2, just checked it with a home test from Ace. What do you all think of pouring a new 2 inch or so floor, maybe Ardex or just concrete? Is 9.2 high enough to worry about? According to the EPA it is so I guess I should do something about it. The home is in Elmhurst, Illinois. Thanks for your feedback.
TB80726
Replies
Where was the 9.2 measured? If it was measured in the basement then you need to re-measure in the living quarters. What time of the year was it measured? Numbers tend to be worse in winter when things are buttoned up tight, though in some cases the draft drawn by a furnace may improve things in the winter.
IIRC, the (somewhat arbitrary) cuttoff is something like 3. If levels upstairs are reasonably well below 3 and you spend no more than a quarter of your time in the basement, calculated year-round, then likely your average exposure is closer to 3 than the 9.2.
Keep in mind that there are many homes with numbers of 20 or greater.
Your options to get rid of the radon are basically sealing, ventillation of the occupied areas (eg, a heat exchanging ventillator), and sucking the radon out before it gets into occupied areas (sub-slab suction).
You are not going to find anyone on Breaktime who knows more about whether that level is harmful than a panel of medical experts who have lab data and established the standard. Since you are somewhat over the recommended action limit you should do something to lower it. That's what the limit means. Children are especially vulnerable, as are people that already have other risk factors for cancer.
With a 6 foot ceiling placing a 2" slab on top is going to make it feel even more cramped. A slab 2" thick over a floor that is already cracked won't hold up either. If you can afford it you'd be better off removing the old slab, excavating deeper, putting in a properly compacted stone base with radon remediation piping buried below, then pouring a nice, new slab of proper thickness with a good finish. Seal the perimeter with concrete backer rod and caulk. That by itself might reduce the radon level sufficiently (you only need to cut it a little more than half). If it doesn't, you can attach a fan to the remediation ductwork to get a further reduction.
Just did the test last week, it was done in a "finished" bedroom that we use every night.
Unfortunately re-grading the floor (financially) is not an option.
After 80 years the floor has cracked about all it is going to (cracked but sound) and I am 5'7" so 2" less head room is ok with me.
The home is a tear down. When we sell in 15 to 20 years it will be gone. It is in an area of crazy property values and tear downs gone wild.
Rather than cement on the floor, if it's dry, I'd consider laying down plastic and those interlocking insulating "tiles" intended for basement floors. You can probably figure out a way to add some vent pipes under the plastic, to draw off the radon.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
If it was me, I would do nothing unless I was trying to sell the house and it became an issue for the buyers. Actually, I had to install radon remediation systems for two houses I owned in the 1980s in IL and OH, but only when it was necessary to get the property sale done. (The second time, the people I bought the house from paid for the under-slab suction system, which I installed later when I had to sell the house).
In my opinion, the EPA levels are arbitrary and excessively low. There are a lot of places where the natural background radiation levels (from nearby mountains, or the concrete in the basement walls, or high altitude, for example) far exceed any radiation from radon gas. Out here in Reno, radon tests are not routinely done at all. When I researched it for my own situation several years ago, it amounted to statistically 1 or 2 more cases of cancer per million people, provided that the person spent 24 hours per day in the basement for 70 years. Your level is a bit higher than mine was, though, and it was measured in the bedroom, not the basement. It also depends on how well ventilated the house is.
Of course, you have to evaluate the risks for yourself, and different people have different comfort levels with that sort of thing. Personally, I think the risk is very small relative to the expense involved and relative to the other risks we take on a daily basis without a thought. Your call, unless you are trying to sell the property to a buyer who makes an issue of it.
Thanks,
Your thoughts make about the most sense to me.
I'm in the process of doing a sub-slab de-pressurization project myself. I'm in SW Iowa and had a level of about 9-10. I don't know why anyone would even think about not doing something to mitigate a radon level above the recommended limits, especially when they spend a fair amount of time in that area. In my opinion, spending a couple hundred $$ is small change compared to the risk of cancer. There is some good info at these sites:
http://www.radonamerica.com/
http://www.infiltec.com/
There are other sites too, but these have good info and can supply components. A book that has lots of good info in it is at the infiltec site, part # RN-MANUAL.
One of the things I've read is that trying to just seal it out has a very small effectiveness.
HTH
A thin slab with a depressurization system should do it.
As I understand it, there is no definite research supporting the EPA's 4 pc/l as the cutoff for radon induced cancer risk. The data used to establish that number is an extrapolation of the established risks from far higher levels found in coal mines. Last I read, no one had hard numbers establishing that as either a safe or an unsafe level. It's just their best guess, and they typically add a 100% safety factor.
"Life'll kill ya." Warren Zevon
Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
The US has one of the most conservative action levels, most countries are 1 1/2 to twice as high; Canada has an action level of about 21 pc/l compared to the US level of 4.
http://tinyurl.com/em8be
You're right, with one exception. It was uranium miners, not coal miners, from which the extrapolation was made.
Basically, they assume that the probability of getting cancer from radon is proportional to dose (which appears to be at least approximately true). Then, knowing the probability at a high dose, they calculate how small of a dose would produce an essentially inconsequental increase in cancer probability (just as an example, it might increase the chances of lung cancer by 1% in a non-smoker).But, for this non-smoker, the chances of lung cancer are vanishingly small to begin with, so in absolute terms this is a very, very small additional risk.And, since probability is (presumably) proportional to dose, 2x or 4x the minimum level is still going to be a very small risk. And, if you only spend, say, 20% of your time in this environment, the risk goes down further.This is not to say that radon mitigation is useless. The cost of mitigation is, in most cases, fairly small (especially in new construction), whereas the social cost of a single case of cancer is in the millions of dollars. But one must maintain a sense of objectivity and proportion -- there's no need to panic at numbers below 100 or so, and it's reasonable to forego mitigation, at least temporarily, when numbers are below 10-20.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
Born and raised in serious radon country where it was unheard of to have radon-related lung cancer. Most of those who got lung cancer were also smoking so that's simply what the cancer was attributed to.
However, there was a row of houses where every family living there had someone develop lung cancer. At first it was just strange, then just considered dumb bad luck after radon and chemical tests came back high but normal. Finally after a couple dozen residents kicked off, the county bought the houses and land just to bulldoze.
It strikes me as even more odd that for every family that moved out of the radon houses there was another jumping for joy to get in.
Houses next to each other in "serious radon country" can vary by 100x or more in the amount of radon they have, based on cracks in the earth, subsoil water flow, etc.It IS critically important to identify and fix the homes with the 100x problems -- these are the ones that are the primary target of all the testing, etc.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison