How should I remediate a radon problem in a new home?

September 5, 2008 8:57 AM

Radon in new home: a newly built home has tested very high for radon -- 16 in the basement and 8 on the first floor. EPA safe level is below 4. How dangerous is radon really, particularly for preschool age children, in terms of a percentage risk for developing cancer? How effective is radon remediation? What technical questions or specs should I insist on and double check? Are there any remediation methods that anyone recommends, that are particularly effective, or that would amount to overkill? Are there any remediation methods that don't work well? And good or bad side effects of radon remediation?
posted by Pastabagel to home & garden (15 comments total)

I'm a Realtor and only ran into this with a relocation client who's company required it. They dug in a big pipe to collect air under the house, put a fan on the end, and retested. The air under the house no longer came into the house, thus the radon was out. It was like $1000 I think.

Did it work? I dunno, the retest passed, which is really the only way to know.

Are you planning to run a daycare there? You'd be crazy not to remedy it in that case.
posted by thilmony at 9:24 AM on September 5, 2008

The is complete conjecture and anecdote... but I am undergoing treatment for thyroid cancer, and after going over my history, the only thing my endo thought might be a cause was the fact that the house I lived in for 14 years as a child tested high for radon, as did an art room at my high school that I spent substantial time in. However, my mother and sister have no cancer issues, so maybe this is a fluke.
posted by kimdog at 9:26 AM on September 5, 2008

Oh... and in both cases (school and home) they closed off the high testing areas, and used large fans to pull out the air for a week or so. Both retested within acceptable ranges.
posted by kimdog at 9:28 AM on September 5, 2008

Radon comes in from the soil under and around your house. Your house acts as a giant wick pulling air from the ground, and with it radon gas. You need to minimize air getting from the ground into your house first, and if that doesn't work you need to actively vent the basement to pull the gas out of the basement to above the roofline of your house.

First, seal off any unsealed surfaces (cinderblock, brick, etc). Simple paint will do the trick. Second, plug any unplugged openings from your basement to the ground (e.g. French drains). Then test again. If you still have high levels, you will need to install an active vent system. It is very simple, and should cost in the neighborhood of $1,000 and will take an two or three hours for someone to do. If you do it yourself (which is easy) it will be more like $250.

In my last house, a high level was fixed instantly by plugging two french drains.
posted by Patapsco Mike at 9:29 AM on September 5, 2008

Radon is a gas that enters your basement through the decay of uranium in the soil or bedrock. Many newer homes are well sealed, while preventing water and bugs to enter actually helps keep the radon in. A ventilation system is often used to vent the radon from below the basement floor to the outside. This usually works very well and with the only side effects being the ugly vent on your house. Call a Radon Remediation company in your area to discuss your options and what has/hasn't been effective in your area.
The EPA has information on Radon & Radon Remediation that I gave to my customers when I worked with Radon testing. The first link has a graph about cancer risks.
Also, did you have a short test (usually 48 hrs) or a long-term test? The longer ones are more accurate. Many homeowners choose to have a longer test (over 90 days) before proceeding with the remediation after a high short test. You may want to install a continuous Radon monitor, even after any remediation, to ensure the remediation is working correctly and your children can breath without worry.
posted by dreaming in stereo at 9:33 AM on September 5, 2008

Oh- as to how dangerous it is, no one knows. It probably increases your risk of certain cancers by fractions of a percent because it is radioactive. But it hardly matters, you might as well fix it because you will have to do it sooner or later (if you ever sell the house) and it's not going to get any cheaper.
posted by Patapsco Mike at 9:33 AM on September 5, 2008

To answer your first question, the EPA says that children don't have a greater risk for lung cancer than adults (although everyone has a definite risk, and you should remedy the problem). Radon is the number one cause of lung cancer among non-smokers.
posted by bluefly at 9:37 AM on September 5, 2008

Also at the bottom of the page I linked to are some statistics on the likelihood of developing cancer given a certain level of radon.
posted by bluefly at 9:46 AM on September 5, 2008

Simple paint will do the trick.

No. See here: "EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently".

If it's a new home, you might have some recourse against the builder. They should have known there was radon in the ground, and they should have used foundation construction techniques more resistant to radon. Presumably, there are no cracks in the concrete foundation wall or floor, but there might be a gap between the concrete floor and walls -- in my house it was 1/8 to 3/8 inch, all the way around. That adds up to a big hole in the floor, and should be sealed with concrete sealant. Also tightly plug any basement floor drains leading to drywells outside, an obvious conduit for soil gases. Then, do a short-term test again as suggested. If the level is down significantly, I would then do a one-year test, so you get the average over a full year, before considering any other actions.

All of this assumes an unfinished basement. If the basement is finished or mostly finished, sealing cracks or surfaces is not an option, and you probably need to proceed directly to the vent method of remediation.

I would get this done, because 16 is not a good reading. On the other hand, it's probably safer than second-hand smoke, so you can take your time. I can't imagine there are negative affects from any remediation method.
posted by beagle at 10:20 AM on September 5, 2008

Oh, and, you didn't say you own this home. If you're looking to buy it, just insist that they do the full vented remediation and you're all set. Insist they seal any foundation gaps also, though.
posted by beagle at 10:22 AM on September 5, 2008

Simple paint will do the trick.

No. See here: "EPA does not recommend the use of sealing alone..."

Keyword here is "alone." Sealing alone won't do it (as I said). It's step one.

And no builder will ever know if a home has radon unless they test for it. I guess it depends on your state/county as to whether a builder is required to test. Here in MD where there is lots of radon testing is not required by either the state or insurance companies.

In a neighborhood of 100 identical homes you could have 4 in different spots that are the only ones with radon. This is not because of foundation issues, it's because radon seeps out through rock fractures underground in a way that is completely unpredictable- resulting in hot spots that are not regularly distributed.
posted by Patapsco Mike at 10:56 AM on September 5, 2008

This isn't quite what you asked, but it may be useful to know: Some mortgage lenders will not provide a loan if a house fails a radon inspection. So even if you decide not to be concerned about it, installing a ventilation system may save you some hassle in the long term.
posted by gnomeloaf at 11:42 AM on September 5, 2008

Our home failed radon tests when we were about to buy it; They simply ran a pipe into a hole in the basement floor and stuck a fan on the end of it above the garage (we're in new construction, so the floor didn't need to be sealed). The house then passed the test- total cost was approx $800 . There are lots of EPA-certified radon remediation contractors out there- the cost probably isn't going to be too bad, depending on your construction.
posted by jenkinsEar at 1:05 PM on September 5, 2008

Im going off the statistics from the Nuclear Reglulatory Commission's Guide 8.29 "Instruction Concerning Risks from Occupational Radiation Exposure"

Going off of the EPA's site a rating of 2 pCi/L gives you a total radiation dose of around 1 rem per year, 8 = 4 rem per year, 16= 8 rem per year. NRC says 1 rem = 0.04% increase in getting cancer which comes out to be, 0.16% increase per year if you stayed on the top floor and a 0.32% increase per year if you stayed in the basement. Which over 18 years becomes 2.88% increase of cancer if you stayed on the top floor and 5.76% increase of cancer if you stayed in the basement.

Unfortunatly these number are for a full grown adult who doesnt spend 24/7 of his time in the house. So for a child I would multiply the above percentages by a number between 2-10 to get the true probability of your child from getting cancer. So to answer your question Radon is EXTREAMLY dangerious and this needs to be fixed.
posted by metex at 1:09 PM on September 5, 2008

When our house was inspected, the radon level was 9 on the ground floor, and we made it a term of sale to have the seller install a vent system. The radon level went down to 4 and we've had no problems with it in the nine years we've owned the house.
posted by lukemeister at 8:11 PM on September 5, 2008