Radon Testing And The Home Buying Process

dreamstime_s_59014320Recently I was showing a property to  first time buyers who fell in love with the home.  They wanted to write a contract and told me the terms.  Now, I had never met them before so we never had a pre-buying meeting where I go through the basics of buying a home.  In the kitchen of the home, I went thru the terms of the contract and got to the section about radon testing.  I asked if they had ever heard about radon gas and they said no.  I proceeded to explain what it was but said it should not be a worry in this particular home since they had recently installed a remediation system and we had a report that showed the radon levels were now way, way below the EPA action level.  At the time they decided to move forward but a day later they backed off because of the “radon issue.”   I know people can throw up all kinds of excuses as to why they don’t want to proceed with a sale so I knew the radon issue could be a smoke screen but here I felt their concern was genuine.

In essence their reasoning went like this, “We will be spending time in the basement so we are very concerned about radon.  We would prefer a home where the levels are below 1 naturally.  What if the remediation system stops working, how will we know?  We would prefer a newer home with a passive system so we don’t have to depend on a fan.  If the home had high levels before, maybe they will continue to grow and the system will not handle it.    And doesn’t that remediation system impact our heating and cooling.  Plus any real estate test is only for 48 hours.  How do we know if a longer test would yield different results?”

Well, there was quite a bit in their argument and while it was real to them, logically and scientifically, they were making a mountain out of a pimple.  Thinking that other buyers may have similar concerns about radon, I thought I would write this post.  I will break down their comments in a bit but first the basics.


Radon is a naturally occurring gas  that is everywhere in the atmosphere.  In high concentrations,  it has been determined that it is the 2nd leading cause of lung cancer behind smoking.   It is odorless and colorless so there is no way to know the levels in your home unless you test.  The EPA states that if there is more than 4 pico curies of radon per liter of air (whatever that is)  the home should be re-mediated.  That’s laymen language.  At the end of this post is a link to the EPA website  where you can get more detailed information.  Please research on your own as I am not a scientist.  Most of what I write below comes from my experience and my research but make no decision based on my thoughts.  Talk to experts in the field to verify or flesh out anything I write here.

BUYER THOUGHT #1  – Find a home that naturally has a reading less than 1

Good luck.  Most of the Northern Virginia area, according to the EPA is in zone 1 which means average radon levels are above 4.  (Here is a link to the EPA national radon map ) While that is nice to know, it does not mean every home has a radon problem.  I spoke with a radon testing company that has over 2 decades of testing experience.  While not quantified, they felt the incidence of homes testing over 4 was about 50% and those testing under 1 without remediation, less than 5%.  It will be a long, long, long search before a buyer finds the right home AND then has a test showing levels below 1.  Since the test doesn’t come until the contract is ratified, this is recipe for lots of blown contracts.  Furthermore, the contract states that the sellers only need to re-mediate if the reading is above 4.  No seller will agree to a contract that says remediation needs to take place if the reading is between 1 and 4 nor will they accept a contract that allows a buyer to back out if the reading is above 1.

These folks also asked me which areas had higher radon.  While, based on my experience, I could guess where I see a greater frequency of higher test results, it means very little.  The radon level inside a home is dependent upon 2 factors – the rocks beneath that home and how tightly wrapped the home is.  If the home is well sealed, radon will more easily accumulate since the exits are blocked.  On the same street 2 homes could have drastically different readings.

Whether true on not I am not sure but I seem to recall being told in a training session years ago that one of the states with the lowest average levels of radon is Alabama but one of the highest home readings ever recorded was in Alabama. It is very home specific.

Let me also note that that EPA scale goes from 1 to 200 with 4 being the action level.  I can tell you in 26 years, I can count on 1 hand the number of homes that tested above 10.  So while our average may put us in zone 1, I am going to guess that we are near the bottom of that group.

BUYER THOUGHTS #2 & #3- What if the remediation system stops working?  We would like a newer home with a passive system.

Here is the good thing about an active remediation system – you will know when it stops working.   With a passive system you will not.

dreamstime_s_38802873I know there are different ways to install remediation systems but in our area it involves installing a sub-slab ventilation system that, in essence, sucks the air out from under the home and blows it outside where it dissipates.   These systems have a U shaped tube on the interior pipe.  There is a liquid inside the U.  If the fan is working, the top ends of the U are uneven.  It the top ends are on the same level, then the fan has stopped working. A working system looks like the picture on the left.

A passive system is just that – passive.  Newer homes have some sort of system that also cause air below the home to go outside. They work but there is no visible way to know if it is working.  The only way is to frequently test.

By the way newer, homes which are more tightly wrapped are probably more likely to read higher than an older home with the same type of geology beneath the home.

BUYER THOUGHT 4 – If it had high levels before, maybe they will grow and and get worse.

Well, radon levels do change over time. And the timing of the test impacts the results.  Remember, radon levels are based on the rocks below the home and the tightness of your home.  Both situations change over time.

Add new windows or doors?  You have changed the air flow in and out of your home – great for heating and cooling but maybe not for radon.

Remember the earthquake a few years back?  That changed the the ground below homes in the area.  In some homes radon was now trapped and levels went down and in others, radon had a clearer path to the surface and radon levels increased.

Dry season or extremely wet?  When the ground is soaked,  readings may be higher.  A high water table forces the gas up and out.

But lets think about this sub slab ventilation system.  The same system is installed whether the initial reading was 4 or 6 or 12.  So if the radon levels change, the system can handle it.  Buy a home with no system because the initial test was low, and you need to periodically retest to make sure things have not changed – no way to know.  I’d feel safer in a home with a remediation system.

BUYER THOUGHT NUMBER 5 – The remediation system will impact out heating an cooling bills

The thought here was that  to install the system a hole was put in the basement floor and a hole in the wall to vent the pipe outside.  But they were sealed.  It is a closed system. Other than the pennies it cost to run the fan, I am not sure how this would impact utility bills.  I have never heard this argument before.  Again, if I was really concerned about radon, remembering that radon is odorless and colorless, I would want visible evidence that the fan is working.


BUYER THOUGHT 6 – It is only a 48 hour test.  Maybe a longer test would produce different results.

This is true but within the scope of a real estate deal a longer test is not possible.  What seller is going to allow a contingency for a 30, 60 or 90 day test when the real estate standard is 48 hours?

Let’s say that the 48 hour test yields a result below 4 requiring no action but after move in a buyer does a test that has a result above 4.  It is not a disaster.  Radon remediation systems cost somewhere between $800 and $1200 to install.  And almost always they bring the radon level below 2 and frequently below 1.  I can not think of one case I’ve had where an after remediation result was above 2.  There may be such homes but I have not seen one.


Is radon a serious health issue?  I will take the scientists at their word and answer yes.  Is it a deal stopper in a real estate deal?  It should not be.

I tell all of my buyer clients that they must get a home inspection but I am ambivalent on a radon test and here is why.  The more contingencies you put into a contract the less appealing it can be to a seller.  To include or not include a radon contingency is situational in my opinion.  If we are the only contract being presented and it is a strong contract, I tell the client to put it in if they want.  But if we are in a multiple contract situation or coming in extremely low, I ask them to think about it.

A home inspection can reveal problems that cost thousands of dollars to repair so you need to know before determining if the home fits your budget parameters.   With radon, your exposure is a $1000 remediation system.  Is it worth pushing a seller over the edge for a $1000 repair?  In a multiple contract situation, a seller may look at a radon contingency as a potential $1000 they need to spend and prefer the contract where they do not have that exposure.  In those situations, I advise client to test after settlement and re mediate on their own.  Then they can use the longer, more accurate tests.

And if all of these still scares you from buying a home, well, the only place to live and not have any radon worries would be a condo on the 2nd floor or above.  Any home that has contact with the ground has potential for radon.  Best option other than a 2nd floor condo? A home with a remediation system in place.

Again, much of what I have written is my opinion.  Research this important topic on your own and let me know if you agree or disagree with any of the above.

If you want more information on radon, here is the link to the EPA site on radon.

4 thoughts on “Radon Testing And The Home Buying Process

  1. Very insightful article and you make some very good points. Yes radon is everywhere and should be mitigated when necessary. Radon testing should be part of every contract. The only way to know.

    Your said
    ” I can tell you in 26 years, I can count on 1 hand the number of homes that tested above 10.”
    ” I can not think of one case I’ve had where an after remediation result was above 2.”

    I recently pulled out on a contract on the house where the radon level average over 48 hours was 11.8. Low of 6.8 and high of 19.2. And this house has a mitigation system in place! Obviously this house and the mitigation system has some issues. If the results were just a little high I say check the mitigation system and retest. But this case it was too risky to accept this issue.

    1. Thank you for your note.

      I wonder if it was a professional mitigation contractor who did the work. Again, I have never had a retest with a reading anywhere near 4. But I 100% agree with you, the only way to know is to test especially since radon is odorless and colorless.

      Where is the house you mentioned?

      Thanks for the input

  2. My husband and I are looking for a house and heard recently that radon is an issue in the area we would like to move to. Your information that we should either look for a house that has a testing of radon levels below 4 or look into radon mitigation is really helpful. I will start looking into radon mitigation companies just in case.

    1. There are radon pockets in the area but it is very specific to the land under your home. Your neighbors could have it and you don’t. Or you could be the only one in the neighborhood with an issue.

      Just test and re mediate if needed.

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