Conducting a radon test on a home with active mitigation

First off I will say I have not yet started radon CE courses for certification, it is next on my list.

While speaking to a perspective client this afternoon, I was looking at the realtors listing and could see an installed radon mitigation system on the side of the house in one of the photos. At the end of the conversation she asked if I would perform a radon test as her agent strongly advised it. I was honest and said “I don’t offer radon testing at this time but would be happy to include the mitigation system in my inspection to make sure it’s working since the home was equipped with one”. Her response was " Oh, uhhhm, well thanks for your time…" , then she hung up. (I don’t want to offer a service I have no certification in so sucks to be me right now…) This scenario kind of got me thinking either the agent or buyer didn’t know the mit. sys. was there or it didn’t work, then asked myself the following questions:

-Has anyone here had clients ask for a radon test on a home with an active and functioning mitigation system in already in place?
-Would a test be warranted if the system was installed correctly and functioning as designed?

  • Wouldn’t you have to shut down the system and wait till possibly the next day to begin a test?

You should still test every two years when a mitigation system has been installed. The contingency period would be an exellent time to start.


An installed radon system may or may not be working effectively. Testing an existing system should be done with the system operating to confirm its effectiveness.
It would not surprise me that it may not be up to par.

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That makes sense. Wouldn’t you have to conduct a second test without the system running as a control to compare results to? How else would you know if the system is effective?

Because he test results would come back as ‘within acceptable standards’ if it’s working. If not, it needs to be repaired/replaced/upgraded. Once you take your formal training, all of this is explained and will make sense. The EPA recommends all homes be tested for Radon every two years, whether it has a mitigation system or not.
Note: mitigation systems are designed to run 24/7/365. It is never turned off during testing, as the house must “pass” while the system is operating.

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I’m in PA where we have the highest average radon levels nationwide, and we do TONS of radon testing (just set two monitors today). First, determining if the system is working doesn’t verify it’s expelling as much radon as it should. It never ceases to amaze me how many homes we test with working systems that come back elevated - often because the fan is inadequate or sewer line work was done leaving cracks in the basement floor. I realize you don’t want to give a response that the agent or client won’t like, but what I’d do in your shoes is offer to find another inspector to just do the radon until you’re certified to do it yourself. I’ve had plenty of calls from other inspectors - mostly retired - who inspect here and there but no longer do radon, and it’s always worked well. Also, just a couple important points for when you do start testing and are dealing with common misconceptions… most agents think that if a system is in place or the home sits on a slab there’s no need to test. Both are false. As I said, systems often don’t work as intended, and some of our highest levels have actually been in slab homes. Hope that helps, and good luck!


NO. You would Never turn off the Radon Fan. All you do is test like you would a home without a mitigation system.

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I know several people with systems in their house that uses a timer and they only run a few hours per day. I take it that would be a call out then?


(I didn’t know Radon only enters a home during certain times of the day!!) :roll_eyes:

Thanks for the input. I’m going to reach out to some other local guys this next week just for this reason.

Me neither!! Always found it odd myself. Thanks Jeffrey.

Thanks, hopefully I can start classes on this weekend. Helps to have at least some understanding on the topic going into it.

Many good posts on this subject. Once or twice a month I get asked to test for radon on an active system.

Stop and think about it simply. YOU can feel or see it running, BUT how well is it working. Without testing you have no real idea. AND if its no longer keeping the levels in the safe zone … IS it the equipment OR has something changed with the house. TEST if asked AND without the fan running you are not testing the system

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Actually it does.
There is radon all the time in every house, but it is not constant and could actually stop a some time of the day/nite.

Just say-en. :upside_down_face: :wink:

Just messing with ya JJ, but I have had leaking HVAC return ducts in the attic/crawl space that pressurize the house significantly to a point Radon can not enter (only when the HVAC is running).

Radon mitigation in schools and commercial buildings is done by building pressurization through an economizer rather than sub-slab depressurization. We have also used this process in large residential houses when air communication below the basement slab could not be achieved.

I know this seldom is used (or happens) but just want to give the OP something more to think about.


Agree, but I must not be on it’s mailing list as I have never received a copy of it’s performance schedule. :wink:


Michael, I don’t know about your state but do you need to have af certification to perform a radon test?? IMHO, if you are doing home inspections, you should be offering radon testing. I would guess about 80% of my inspections include radon testing. Here are 2 used Sun Nuclear 1028s at a very reasonable price. . At this price, they will pay for themselves after 4 inspections. You can also buy charcoal canisters for testing but then you are at the mercy of the mail (which ain’t good right now) and the mercy of the lab. I’ve found dealing with labs can be very frustrating. Quick results without hassle is the key. I test a lot of houses with mitigation systems. No reason not to.

Not sure if mentioned yet, but several companies in my area offer testing along with other services such as termite inspections and radon mitigation. Hiring one of these companies to do the testing for you may be the way to start with radon, because there is not up front cost of buying equipment and classes.


Yup! Don’t loose work because you don’t do something!
Doing commercial inspections your expected to bring in several subs.
Before I got equipment, I worked a deal with a local inspector where I picked up equipment on my way to work. I just paid him his going fees so I could service my clients as needed.

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In CO there are no requirements for it so anyone can do testing. Guess I am too honest. Would feel better if I could show credentials when asked to say that I am certified. That’s my next project…

Thanks to you all that posted, I appreciate it. A lot of good ensight and things to ponder. My questions were definitely answered.