The validity of doing radon tests

You can also edit the NACHI agreement so it fits into your style of testing.

That’s actually what mine is that I posted above. I replaced the charcoal info with CRM, and adjusted a few other things to my liking.


I wouldn’t freak out too much about the tampering deal. The vast majority of people are honest.

Make some door hangers to hang on the tripod and near the front door of the home. You can write them up saying all kinds of things like “Temperature, humidity, and pressure sensors in use, any unusual change in readings will invalidate the radon test.” Make it big and scary and official sounding. Put your contact info on the hanger and give yourself a big title like Certified Professional Radon Measurement Contractor and put your NACHI number on it. Tape one to the patio door and maybe a few windows if you really want to. The homeowners will be moving in and out of the doors as fast as possible, lol. :joy: :joy:

Here’s the one I use. I didn’t make it sound too scary though.

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In all reality, the ability for a home owner to modify the environment without the inspectors knowledge would likely release the inspector of all liability. Follow the protocols, have the certifications and professional equipment and all is well.

What you want to avoid is gross negligence.


Release of liability for test tampering should be spelled out in your contract or a separate addendum (which becomes part of the contract). It might also be helpful to inform anyone involved that the ‘stack effect’ can increase the readings when windows are opened.

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The NRPP cert is not required in MD - do you mind me asking do you have yours?
If i keep getting deeper in the HI - ill probably end up getting it.

That is one thing I always make sure I tell the homeowner before they sign the radon test authorization form. I tell them opening windows may actually raise the radon level, I uusually get that look, since most know little about radon, especially how it enters the home. I believe that helps keep a lot of windows closed.

I can tell you in the +/- 3000 tests we’ve performed I’ve never had a real instance of this. The worst thing I can remember is someone sold a house a few years later and their buyers had a drastically different result so just to help out we went and re-tested for free. Our test was inline with our initial one and I’m not sure what ever happened. In any case, radon callbacks and general BS is at a far lower rate than general inspections in my experience.

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Environmental monitors on the device can give you an idea about closed house conditions. Shifts in radon reading, temperature, and humidity are a hint. I have had only a few where I suspect closed house conditions being compromised. One time I asked the seller of they were in the basement, accessed through the exterior only, at such and such time. They left the door ajar for a couple hours, which showed up.

I’m going to add as an edit; My required Notification that stays near the device has the set and pick up times on it. I often in fact set the test start and thus the end on the device to a different time by a few hours. That way if the seller is trying to cheat for what they think is the device recording period, and they reestablish proper conditions at the time my Notification says the test ends, they are choosing the wrong times. Like above, explaining stack effect and how it can increase radon readings is another good ploy.

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Do a short term test on your own home using a CRM or whatever device you normally use. Then do a 6 month test using an alpha track monitor. Find out for yourself. I doubt you will ever see a drastic difference.

My own home; I’ve done quite a few short term tests which have a 48 hour average around 1.3 to 1.6. I did an alpha track monitor test for 6 months that was 1.5 pCi/L. That is well within the Relative Percent Difference at that reading; meaning good results.